Gymnastics - 2021 European Artistic Gymnastics Championships - St. Jakobshalle, Basel, Switzerland - April 22, 2021 France's Leo Saladino puts chalk on the parallel bars REUTERS/Arnd Wiegmann

Vendors play dominoes while waiting for customers in an alley of souvenir shops at a tourist market, amid the coronavirus disease (COVID-19) pandemic in Luxor, Egypt April 9, 2021. Picture taken April 9, 2021. REUTERS/Amr Abdallah Dalsh

A man walks through an alley of souvenir shops at a tourist market, amid the coronavirus disease (COVID-19) pandemic in Luxor, Egypt April 9, 2021. Picture taken April 9, 2021. REUTERS/Amr Abdallah Dalsh

U.S. Secretary of State Antony Blinken participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

Gymnastics - 2021 European Artistic Gymnastics Championships - St. Jakobshalle, Basel, Switzerland - April 22, 2021 Italy's Carlo Macchini in action during the Men's Horizontal Bar REUTERS/Arnd Wiegmann

People walk through an alley of souvenir shops at a tourist market, amid the coronavirus disease (COVID-19) pandemic in Luxor, Egypt April 9, 2021. Picture taken April 9, 2021. REUTERS/Amr Abdallah Dalsh

A horse cart guide waits for customers next to an alley of souvenir shops in front of a tourist market, amid the coronavirus disease (COVID-19) pandemic in Luxor, Egypt April 9, 2021. Picture taken April 9, 2021. REUTERS/Amr Abdallah Dalsh

Tennis - WTA 500 - Stuttgart Open - Porsche-Arena, Stuttgart, Germany - April 22, 2021 Belarus' Aryna Sabalenka in action during her round of 16 match against Germany's Anna-Lena Friedsam Pool via REUTERS/Thomas Kienzle

Tennis - WTA 500 - Stuttgart Open - Porsche-Arena, Stuttgart, Germany - April 22, 2021 Germany's Anna-Lena Friedsam in action during her round of 16 match against Belarus' Aryna Sabalenka Pool via REUTERS/Thomas Kienzle

Gymnastics - 2021 European Artistic Gymnastics Championships - St. Jakobshalle, Basel, Switzerland - April 22, 2021 Russia's Kirill Prokopev in action during the Men's Pommel Horse REUTERS/Arnd Wiegmann

View of the town of Halki, amid the coronavirus disease (COVID-19) pandemic, on the island of Halki, Greece, April 13, 2021. Picture taken April 13, 2021. Picture taken with a drone. REUTERS/Vassilis Triandafyllou

View of the town of Halki, amid the coronavirus disease (COVID-19) pandemic, on the island of Halki, Greece, April 13, 2021. Picture taken April 13, 2021. Picture taken with a drone. REUTERS/Vassilis Triandafyllou

U.S. Vice President Kamala Harris participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden walks towards a podium before participating in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

World leaders appear on screen during a virtual Climate Summit, seen from the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. Vice President Kamala Harris is reflected in a tablet screen while participating in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

John Kerry, Special Presidential Envoy for Climate, looks up at a video screen while participating in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

John Kerry, Special Presidential Envoy for Climate, looks up at a video screen while participating in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden puts his protective face mask on following his remarks in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. Vice President Kamala Harris participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden delivers remarks in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

U.S. President Joe Biden takes his face mask off before delivering remarks in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

Medical workers stand near medical materials at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

U.S. Vice President Kamala Harris participates in a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

Iraqi woman swimming trainer Elaf, 35, teaches a child how to swim and dive, amid the outbreak of the coronavirus disease (COVID-19), at a swimming pool in Basra, Iraq, April 22, 2021. REUTERS/Essam al-Sudani

A patient suffering from the coronavirus disease (COVID-19) uses his phone at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

A patient suffering from the coronavirus disease (COVID-19) talks on a phone at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) lay in beds at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

U.S. Vice President Kamala Harris is seen on the screen as Mexico's President Andres Manuel Lopez Obrador attends a virtual U.S. global climate summit, at the National Palace in Mexico City, Mexico, April 22, 2021. REUTERS/Henry Romero

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Messages of gratitude from patients to medical workers are seen on a wall at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

U.S. Vice President Kamala Harris is seen on the screen as Mexico's President Andres Manuel Lopez Obrador attends a virtual U.S. global climate summit, at the National Palace in Mexico City, Mexico, April 22, 2021. REUTERS/Henry Romero

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

A medical worker treats patients suffering from the coronavirus disease (COVID-19) at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

A note reading "Thank you" is seen on a wall as medical workers treat patients suffering from the coronavirus disease (COVID-19) at the Stark Arena sports venue that is turned into a COVID-19 hospital in Belgrade, Serbia, April 22, 2021. REUTERS/Marko Djurica

U.S. President Joe Biden and Vice President Kamala Harris walk on stage for a virtual Climate Summit with world leaders in the East Room at the White House in Washington, U.S., April 22, 2021. REUTERS/Tom Brenner

An elk is seen in a burnt forest in the Chernobyl zone, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

A damaged panel is seen in a control centre of the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An interior view shows the house in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

A house is seen in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant in Ukraine April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

An employee walks through a corridor of the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

A calendar is seen on the wall in a house in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An employee walks down the stairs at the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

Constructions of a Soviet made over-the-horizon (OTH) radar system "Duga" are seen near the Chernobyl Nuclear Power Plant, Ukraine, April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

An employee is seen in the reactor hall of the stopped third bloc at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An interior view shows the house in the abandoned village of Zalissya near the Chernobyl Nuclear Power Plant in Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An employee walks at a control centre of the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich TPX IMAGES OF THE DAY

An elk is seen on a road in the Chernobyl zone, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

Children's beds are seen in a kindergarten near the Chernobyl Nuclear Power Plant in the abandoned city of Pripyat, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An employee is seen in the reactor hall of the stopped third bloc at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

The coat of arms of the Soviet Union is seen on the roof of a building in the abandoned city of Pripyat near the Chernobyl Nuclear Power Plant, Ukraine, April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

A Przewalski's horse is seen in a burnt forest in the Chernobyl zone, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

A view shows the abandoned village of Poliske in the Chernobyl zone, Ukraine April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

A house is seen in the abandoned village of Poliske near the Chernobyl Nuclear Power Plant, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An employee undergoes a radioactive contamination check near the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

A New Safe Confinement (NSC) structure over the old sarcophagus covering the damaged fourth reactor at the Chernobyl Nuclear Power Plant is seen behind the abandoned town of Pripyat, Ukraine April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

A view shows the abandoned city of Pripyat near the Chernobyl Nuclear Power Plant, Ukraine, April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

Toys are seen in a kindergarten near the Chernobyl Nuclear Power Plant in the abandoned city of Pripyat, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

A view shows the abandoned city of Pripyat near the Chernobyl Nuclear Power Plant, Ukraine, April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

An employee walks through a corridor of the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

A child's gas mask is seen in a kindergarten near the Chernobyl Nuclear Power Plant in the abandoned city of Pripyat, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An employee is seen in a control centre of the stopped third reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

Remains of burnt houses are seen in the abandoned village of Poliske in the Chernobyl zone, Ukraine April 12, 2021. Picture taken with a drone April 12, 2021. REUTERS/Gleb Garanich

An employee walks at a control centre of the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

A vintage doll, which was placed by a visitor, is seen on a bed at a kindergarten near the Chernobyl Nuclear Power Plant in the abandoned city of Pripyat, Ukraine April 12, 2021. Picture taken April 12, 2021. REUTERS/Gleb Garanich

An employee gestures in a corridor near the damaged fourth reactor at the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich

An employee is reflected in a control centre of the Chernobyl Nuclear Power Plant in Chernobyl, Ukraine March 25, 2021. Picture taken March 25, 2021. REUTERS/Gleb Garanich