Carin Winter (L), who had a family member who survived 9/11 and who teaches mindfulness in schools, leads a meditation with other survivors of mass trauma, (2nd L-R) Heather Martin of Columbine, Sherrie Lawson of Washington Navy Yard, Kaylan Bailey of the Aurora Theater shooting, Edie Lutnick who lost her brother in 9/11, Mike Dempsey who survived the Route 91 Las Vegas shooting and 9/11, at a breakfast for mass trauma survivors in Coral Springs, Florida, U.S., April 2, 2019. The Rebels Project members were invited to Florida to participate in a Parkland MSD Community Peer Support Event organized by Dempsey. REUTERS/Leah Millis SEARCH "COLUMBINE SURVIVOR" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. THE IMAGES SHOULD ONLY BE USED TOGETHER WITH THE STORY - NO STAND-ALONE USES. 

U.S. President Barack Obama walks into the Oval Office upon his return to the White House in Washington September 25, 2015. Obama was at nearby Ft. Myer in Virginia for the retirement ceremony of the Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey. REUTERS/Kevin Lamarque

U.S. President Barack Obama applauds as outgoing chairman of the Joint Chiefs of Staff Martin Dempsey (C) shakes hands with his successor Marine Gen. Joseph Dunford (R) at his retirement ceremony at Ft. Myer in Arlington, Virginia September 25, 2015. REUTERS/Kevin Lamarque

Outgoing Chairman of the Joint Chiefs of Staff Martin Dempsey (R) swears in his successor Marine Gen. Joseph Dunford at his retirement ceremony at Ft. Myer in Arlington, Virginia September 25, 2015. REUTERS/Kevin Lamarque

Outgoing Chairman of the Joint Chiefs of Staff Martin Dempsey (L) inspects the Old Guard Fife and Drum Corps at his retirement ceremony at Ft. Myer in Arlington, Virginia September 25, 2015. Dempsey will be replaced by Marine Gen. Joseph Dunford. REUTERS/Kevin Lamarque

U.S. President Barack Obama shakes hands with outgoing Chairman of the Joint Chiefs of Staff Martin Dempsey at his retirement ceremony at Ft. Myer in Arlington, Virginia September 25, 2015. Dempsey will be replaced by Marine Gen. Joseph Dunford. At left is U.S. Secretary of Defense Ash Carter. REUTERS/Kevin Lamarque

The Chairman of the Joint Chiefs of Staff, U.S.Army General Martin Dempsey (R), along with Energy Secretary Ernest Moniz, (L), appear before the Senate Armed Services Committee in Washington July 29, 2015. Secretary of State John Kerry intensified efforts on Tuesday to beat back criticism of the Iran nuclear deal and convince U.S. lawmakers that rejecting it would give Tehran a fast track to a weapon and access to billions of dollars from collapsed sanctions. REUTERS/Gary Cameron 

The Chairman of the Joint Chiefs of Staff, U.S.Army General Martin Dempsey, appears before the Senate Armed Services Committee in Washington July 29, 2015. Secretary of State John Kerry intensified efforts on Tuesday to beat back criticism of the Iran nuclear deal and convince U.S. lawmakers that rejecting it would give Tehran a fast track to a weapon and access to billions of dollars from collapsed sanctions. REUTERS/Gary Cameron 

(L-R) U.S. Secretary of State John Kerry, Secretary of the Treasury Jack Lew, Secretary of Defense Ash Carter, Energy Secretary Ernest Moniz and Joint Chiefs of Staff Chairman U.S. Army General Martin Dempsey appear before the Senate Armed Services Committee in Washington July 29, 2015. Several Obama administration cabinet members continue to testify before Congressional committees on the recent Iran nuclear deal. REUTERS/Gary Cameron 

U.S. Secretary of Defense Ash Carter (L) and Chairman of the Joint Chiefs of Staff General Martin Dempsey testify during a Senate Armed Services Committee hearing on "Counter-ISIL (Islamic State of Iraq and the Levant) Strategy" on Capitol Hill in Washington, United States, July 7, 2015. The United States was only training about 60 Syrian opposition fighters to battle Islamic State as of July 3, far below expectations, partly due to rigorous U.S. vetting of recruits, Carter told Congress on Tuesday. REUTERS/Kevin Lamarque

U.S. Secretary of Defense Ash Carter (L) and Chairman of the Joint Chiefs of Staff General Martin Dempsey testify during a Senate Armed Services Committee hearing on "Counter-ISIL (Islamic State of Iraq and the Levant) Strategy" on Capitol Hill in Washington, United States, July 7, 2015. The United States was only training about 60 Syrian opposition fighters to battle Islamic State as of July 3, far below expectations, partly due to rigorous U.S. vetting of recruits, Carter told Congress on Tuesday. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY

U.S. Secretary of Defense Ash Carter (L) and Chairman of the Joint Chiefs of Staff General Martin Dempsey testify during a Senate Armed Services Committee hearing on "Counter-ISIL (Islamic State of Iraq and the Levant) Strategy" on Capitol Hill in Washington, United States, July 7, 2015. The United States was only training about 60 Syrian opposition fighters to battle Islamic State as of July 3, far below expectations, partly due to rigorous U.S. vetting of recruits, Carter told Congress on Tuesday. REUTERS/Kevin Lamarque

U.S. Secretary of Defense Ash Carter (L) and Chairman of the Joint Chiefs of Staff General Martin Dempsey testify during a Senate Armed Services Committee hearing on "Counter-ISIL (Islamic State of Iraq and the Levant) Strategy" on Capitol Hill in Washington, United Styates, July 7, 2015. The United States was only training about 60 Syrian opposition fighters to battle Islamic State as of July 3, far below expectations, partly due to rigorous U.S. vetting of recruits, Carter told Congress on Tuesday. REUTERS/Kevin Lamarque

U.S. Secretary of Defense Ash Carter (L) and Chairman of the Joint Chiefs of Staff General Martin Dempsey testify during a Senate Armed Services Committee hearing on "Counter-ISIL (Islamic State of Iraq and the Levant) Strategy" on Capitol Hill in Washington, United States, July 7, 2015. The United States was only training about 60 Syrian opposition fighters to battle Islamic State as of July 3, far below expectations, partly due to rigorous U.S. vetting of recruits, Carter told Congress on Tuesday. REUTERS/Kevin Lamarque

Chairman of the Joint Chiefs of Staff General Martin Dempsey testifies during a Senate Armed Services Committee hearing on "Counter-ISIL (Islamic State of Iraq and the Levant) Strategy" on Capitol Hill in Washington, United States, July 7, 2015. The United States was only training about 60 Syrian opposition fighters to battle Islamic State as of July 3, far below expectations, partly due to rigorous U.S. vetting of recruits, Defense Secretary Ash Carter told Congress on Tuesday. REUTERS/Kevin Lamarque

U.S. Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff General Martin Dempsey take their seats to testify at a Senate Armed Services Committee hearing on "Counter-ISIL (Islamic State of Iraq and the Levant) Strategy" on Capitol Hill in Washington July 7, 2015. The United States was only training about 60 Syrian opposition fighters to battle Islamic State as of July 3, far below expectations, partly due to rigorous U.S. vetting of recruits, Carter told Congress on Tuesday. REUTERS/Kevin Lamarque

U.S. President Barack Obama (L) is flanked by Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (2nd R) and Vice Chairman U.S. Navy Admiral Sandy Winnefeld (R) as he delivers remarks after a briefing on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (L) is flanked by Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (2nd R) and Vice Chairman U.S. Navy Admiral Sandy Winnefeld (R) as he delivers remarks after a briefing on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C) is flanked by Defense Secretary Ash Carter (L), General David Rodriguez (2nd L) and Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (R) as he delivers remarks after a briefing on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C), flanked by Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (R), listens to a question from a reporter after his remarks following a briefing on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C), flanked by Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (R), pauses as he delivers remarks after a briefing on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C) sits down to a meeting with Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (R), for an update on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (L) sits down to a meeting with Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (R) and other officials for an update on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (2nd L) sits down to a meeting with Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (3rd L), for an update on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C) sits down to a meeting with Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (R), for an update on U.S. efforts against the Islamic State (ISIS), at the Pentagon in Arlington, Virginia July 6, 2015. REUTERS/Jonathan Ernst 

U.S. Defense Secretary Ash Carter (L) speaks next to Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey at their joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey (R) speaks next to U.S. Defense Secretary Ash Carter at their joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey hold a joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey hold a joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey hold a joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) speaks next to Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey at their joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) speaks next to Chairman of the Joint Chiefs of Staff, General Martin Dempsey at their joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) speaks next to Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey at their joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey hold a joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey hold a joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (L) speaks next to Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey at their joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Defense Secretary Ash Carter (C) and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey arrive at a joint news conference at the Pentagon in Washington July 1, 2015. REUTERS/Yuri Gripas 

U.S. Joint Chiefs Chairman General Martin Dempsey arrives to testify before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

A protester holds a sign as U.S. Defense Secretary Ash Carter and U.S. Joint Chiefs Chairman General Martin Dempsey (unseen) testify before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

U.S. Defense Secretary Ash Carter testifies before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, accompanied by U.S. Joint Chiefs Chairman General Martin Dempsey (R), on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

U.S. Joint Chiefs Chairman General Martin Dempsey listens as U.S. Defense Secretary Ash Carter (not pictured) testifies before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

U.S. Joint Chiefs Chairman General Martin Dempsey listens as U.S. Defense Secretary Ash Carter (L) testifies before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

U.S. Joint Chiefs Chairman General Martin Dempsey arrives to testify before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

U.S. Joint Chiefs Chairman General Martin Dempsey listens as U.S. Defense Secretary Ash Carter (L) testifies before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

U.S. Defense Secretary Ash Carter and U.S. Joint Chiefs Chairman General Martin Dempsey (R) arrive to testify before a House Armed Services Committee hearing on U.S. Policy and Strategy in the Middle East, on Capitol Hill in Washington June 17, 2015. REUTERS/Carlos Barria 

Israel's President Reuven Rivlin (R) shakes hands with Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey during their meeting in Jerusalem June 10, 2015. Rivlin expressed his concern to the United States on Wednesday about the fate of the Druze minority in Syria, saying around 500,000 of them were under threat from Islamist militants in an area near the Israeli border. REUTERS/Ronen Zvulun

Israel's President Reuven Rivlin (R) meets Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey in Jerusalem June 10, 2015. Rivlin expressed his concern to the United States on Wednesday about the fate of the Druze minority in Syria, saying around 500,000 of them were under threat from Islamist militants in an area near the Israeli border. REUTERS/Ronen Zvulun 

Israel's President Reuven Rivlin (R) shakes hands with Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey during their meeting in Jerusalem June 10, 2015. Rivlin expressed his concern to the United States on Wednesday about the fate of the Druze minority in Syria, saying around 500,000 of them were under threat from Islamist militants in an area near the Israeli border. REUTERS/Ronen Zvulun

General Martin E. Dempsey, chairman of the Joint Chiefs of Staff, delivers a statement after a welcoming ceremony in Tel Aviv June 9, 2015. REUTERS/Baz Ratner

General Martin E. Dempsey, chairman of the Joint Chiefs of Staff, arrives to deliver a statement after a welcoming ceremony in Tel Aviv June 9, 2015. REUTERS/Baz Ratner

Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (L) is escorted by Israel's Chief of Staff Lieutenant General Gadi Eizenkot during a welcoming ceremony for Dempsey in Tel Aviv June 9, 2015. REUTERS/Baz Ratner

Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey, is escorted by Israel's Chief of Staff Lieutenant General Gadi Eizenkot (front R) during a welcoming ceremony for Dempsey in Tel Aviv June 9, 2015. REUTERS/Baz Ratner

Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (2ndR) and Israel's Chief of Staff Lieutenant General Gadi Eizenkot (R) greet Israeli army officers during a welcoming ceremony for Dempsey in Tel Aviv June 9, 2015. REUTERS/Baz Ratner

General Martin E. Dempsey, chairman of the Joint Chiefs of Staff, is escorted by Israel's Chief of Staff Lieutenant General Gadi Eizenkot (R) during a welcoming ceremony for Dempsey in Tel Aviv June 9, 2015. REUTERS/Baz Ratner

Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (from 3rd R), U.S. Defense Secretary Ash Carter and President Barack Obama bow their heads during an invocation by U.S. Army Chaplain Gary Studniewski (L) during the Memorial Day observance at Arlington National Cemetery in Arlington, Virginia May 25, 2015. REUTERS/Jonathan Ernst 

People cheer and applaud remarks by Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (not pictured) during the Memorial Day observance at Arlington National Cemetery in Arlington, Virginia May 25, 2015. REUTERS/Jonathan Ernst 

Members of the official party, including Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (L) and U.S. Defense Secretary Ash Carter (2nd L), applaud remarks by U.S. President Barack Obama at the Memorial Day observance at Arlington National Cemetery in Arlington, Virginia May 25, 2015. REUTERS/Jonathan Ernst 

Participants applaud U.S. President Barack Obama (C) as he rises to deliver remarks at the Memorial Day observance at Arlington National Cemetery in Arlington, Virginia May 25, 2015. Also pictured are Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (L), U.S. Defense Secretary Ash Carter (2nd L), U.S. Army Military District of Washington Commanding General Jeffrey Buchanan (2nd R) and U.S. Army Chaplain Gary Studniewski (R). REUTERS/Jonathan Ernst 

Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (L-R), U.S. Defense Secretary Ash Carter and President Barack Obama stand for the playing of taps during the Memorial Day observance at Arlington National Cemetery in Arlington, Virginia May 25, 2015. REUTERS/Jonathan Ernst 

Chairman of the Joint Chiefs of Staff U.S. Army General Martin Dempsey (L-R), U.S. Defense Secretary Ash Carter and President Barack Obama bow their heads in prayer during the Memorial Day observance at Arlington National Cemetery in Arlington, Virginia May 25, 2015. REUTERS/Jonathan Ernst