People attend a ceremony to float out the nuclear-powered icebreaker "Sibir" (Siberia), which is under construction, at the Baltic Shipyard in St. Petersburg, Russia September 22, 2017. REUTERS/Anton Vaganov 

People attend a ceremony to float out the nuclear-powered icebreaker "Sibir" (Siberia), which is under construction, at the Baltic Shipyard in St. Petersburg, Russia September 22, 2017. REUTERS/Anton Vaganov 

An icebreaker built for the Finnish government is seen at Arctech Helsinki Shipyard in Helsinki, Finland, September 10, 2015. The world's biggest manufacturer of icebreakers, or ships that can navigate ice-covered waters, Arctech is poised to benefit from an expected flurry of activity in the Arctic, which is being reinforced by U.S. President Barack Obama's Arctic push. Picture taken September 10, 2015. REUTERS/Jussi Rosendahl 

An icebreaker built for the Finish government is seen at Arctech Helsinki Shipyard in Helsinki, Finland, September 10, 2015. The world's biggest manufacturer of icebreakers, or ships that can navigate ice-covered waters, Arctech is poised to benefit from an expected flurry of activity in the Arctic, which is being reinforced by U.S. President Barack Obama's Arctic push. Picture taken September 10, 2015. REUTERS/Jussi Rosendahl 

An icebreaker built for the Russian Ministry of Transport is seen at Arctech Helsinki Shipyard in Helsinki, Finland, September 10, 2015. The world's biggest manufacturer of icebreakers, or ships that can navigate ice-covered waters, Arctech is poised to benefit from an expected flurry of activity in the Arctic, which is being reinforced by U.S. President Barack Obama's Arctic push. Picture taken September 10, 2015. REUTERS/Jussi Rosendahl 

A U.S. Coast Guard vessel patrols nearby as U.S. President Barack Obama takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama delivers remarks before taking a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama views Bear Glacier on a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama views Bear Glacier on a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

A restaurant patron holds up his baby to greet U.S. President Barack Obama in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama views Bear Glacier on a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama views Bear Glacier on a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama views Bear Glacier on a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst TPX IMAGES OF THE DAY

U.S. President Barack Obama takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama views Bear Glacier on a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

A U.S. Coast Guard vessel patrols nearby as U.S. President Barack Obama (2nd L, at bow of boat in background) takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (L) takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (L) takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (L, in bow of boat) takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (L, in bow of boat) takes a boat tour of Kenai Fjords National Park in Seward, Alaska September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama arrives aboard the Marine One helicopter in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

U.S. President Barack Obama hikes with National Park Service staffs to the Exit Glacier at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

A general view of the Exit Glacier is seen at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

A general view of the Exit Glacier is seen at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

Security personnels wait for U.S. President Barack Obama to arrive aboard the Marine One helicopter in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

U.S. President Barack Obama arrives aboard the Marine One helicopter in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

U.S. President Barack Obama (2nd R) arrives aboard the Marine One helicopter in Seward, Alaska September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama hikes to the Exit Glacier at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

U.S. President Barack Obama stops to make remarks to reporters as he hikes to the Exit Glacier at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

U.S. President Barack Obama arrives aboard the Marine One helicopter in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama stops to make remarks to reporters as he hikes to the Exit Glacier at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst? 

U.S. President Barack Obama hikes to the Exit Glacier at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama hikes to the Exit Glacier at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

U.S. President Barack Obama stops to make remarks to reporters as he hikes to the Exit Glacier at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst TPX IMAGES OF THE DAY

U.S. President Barack Obama stops to view the Exit Glacier on a hiking trail at Kenai Fjords National Park in Seward, Alaska, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic and the United States has fallen far behind Russian resources. REUTERS/Jonathan Ernst 

The bow of the USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The hull of the USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The bow of the USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The hull of the USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The battered and barnacle-covered hull of the USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

The USCGC Polar Sea is shown dockside at the U.S. Coast Guard Base in Seattle, Washington, September 1, 2015. President Barack Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. REUTERS/David Ryder 

U.S. President Barack Obama asks members of the traveling press corps if they would like a pastry as he orders at Snow City Cafe in Anchorage, Alaska, September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. The move, part of a push to convince Americans to support Obama's plans to curb climate change, has long been urged by Arctic advocates as climate change opens up the region to more shipping, mining and drilling. REUTERS/Jonathan Ernst 

U.S. President Barack Obama makes a pastry order at Snow City Cafe in Anchorage, Alaska, September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. The move, part of a push to convince Americans to support Obama's plans to curb climate change, has long been urged by Arctic advocates as climate change opens up the region to more shipping, mining and drilling. REUTERS/Jonathan Ernst 

U.S. President Barack Obama makes a pastry order at Snow City Cafe in Anchorage, Alaska, September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. The move, part of a push to convince Americans to support Obama's plans to curb climate change, has long been urged by Arctic advocates as climate change opens up the region to more shipping, mining and drilling. REUTERS/Jonathan Ernst 

U.S. President Barack Obama signs a book for children as he greets patrons at Snow City Cafe in Anchorage, Alaska, September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. The move, part of a push to convince Americans to support Obama's plans to curb climate change, has long been urged by Arctic advocates as climate change opens up the region to more shipping, mining and drilling. REUTERS/Jonathan Ernst 

U.S. President Barack Obama greets people at Snow City Cafe in Anchorage, Alaska, September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. The move, part of a push to convince Americans to support Obama's plans to curb climate change, has long been urged by Arctic advocates as climate change opens up the region to more shipping, mining and drilling. REUTERS/Jonathan Ernst 

U.S. President Barack Obama makes a pastry order at Snow City Cafe in Anchorage, Alaska, September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. The move, part of a push to convince Americans to support Obama's plans to curb climate change, has long been urged by Arctic advocates as climate change opens up the region to more shipping, mining and drilling. REUTERS/Jonathan Ernst 

U.S. President Barack Obama greets patrons in Snow City Cafe in Anchorage, Alaska, September 1, 2015. Obama on Tuesday proposed a faster timetable for buying a new heavy icebreaker for the U.S. Arctic, where quickly melting sea ice has spurred more maritime traffic, and the United States has fallen far behind Russian resources. The move, part of a push to convince Americans to support Obama's plans to curb climate change, has long been urged by Arctic advocates as climate change opens up the region to more shipping, mining and drilling. REUTERS/Jonathan Ernst 

United States Coast Guard ships are shown in this aerial photo near Whitefish Bay on Lake Superior northwest of Sault Ste. Marie, Ontario April 7, 2015. The icebreakers are participating in an effort to free eight freighters from heavy ice in eastern Lake Superior as the biggest ice cover on the Great Lakes in decades is backing up shipments of everything from Canadian grain to U.S. iron and steel in one of North America's most important economic regions. REUTERS/Kenneth Armstrong 

The Canadian Coast Guard Ship (CCGS) Samuel Risley is shown in this aerial photo near Whitefish Bay on Lake Superior northwest of Sault Ste. Marie, Ontario April 7, 2015. The icebreaker was participating in an effort to free eight freighters from heavy ice in eastern Lake Superior as the biggest ice cover on the Great Lakes in decades is backing up shipments of everything from Canadian grain to U.S. iron and steel in one of North America's most important economic regions. REUTERS/Kenneth Armstrong 

The Canadian Coast Guard Ship (CCGS) Samuel Risley (L) is shown in this aerial photo near Whitefish Bay on Lake Superior northwest of Sault Ste. Marie, Ontario April 7, 2015. The icebreaker was participating in an effort to free eight freighters from heavy ice in eastern Lake Superior as the biggest ice cover on the Great Lakes in decades is backing up shipments of everything from Canadian grain to U.S. iron and steel in one of North America's most important economic regions. REUTERS/Kenneth Armstrong 

The Canadian Coast Guard Ship (CCGS) Samuel Risley is shown in this aerial photo near Whitefish Bay on Lake Superior northwest of Sault Ste. Marie, Ontario April 7, 2015. The icebreaker was participating in an effort to free eight freighters from heavy ice in eastern Lake Superior as the biggest ice cover on the Great Lakes in decades is backing up shipments of everything from Canadian grain to U.S. iron and steel in one of North America's most important economic regions. REUTERS/Kenneth Armstrong 

Crew member Paul Mullen Jr. looks out at the ice as the Warren Jr., a 150 foot offshore supply boat, works as an ice breaker for the commuter ferry in the waters off Hingham, Massachusetts, March 3, 2015. With its black hull rumbling against a field of broken ice, the Warren Jr. slowly eased away from a dock in the Boston suburb of Hingham on Tuesday, aiming to clear a path for some of the four ferries that carry commuters from here into the city each day. But in a sign of how long Massachusetts has been gripped by freezing temperatures, no other vessels followed, as the tide narrowed the channel behind the ocean-going supply boat pressed into service as an icebreaker. It was the 15th day of canceled ferry service since late January and the outing was meant to speed the fleet's return to service, which could still be days away. REUTERS/Brian Snyder (UNITED STATES - Tags: ENVIRONMENT TRANSPORT) 

Crew member Paul Mullen Jr. looks out at the ice as the Warren Jr., a 150 foot offshore supply boat, works as an ice breaker for the commuter ferry in the waters off Hingham, Massachusetts March 3, 2015. With its black hull rumbling against a field of broken ice, the Warren Jr. slowly eased away from a dock in the Boston suburb of Hingham on Tuesday, aiming to clear a path for some of the four ferries that carry commuters from here into the city each day. But in a sign of how long Massachusetts has been gripped by freezing temperatures, no other vessels followed, as the tide narrowed the channel behind the ocean-going supply boat pressed into service as an icebreaker. It was the 15th day of canceled ferry service since late January and the outing was meant to speed the fleet's return to service, which could still be days away. REUTERS/Brian Snyder (UNITED STATES - Tags: ENVIRONMENT TRANSPORT)