Weapons of mass destruction

President Donald Trump speaks in the Cabinet Room of the White House in Washington, Monday, April 9, 2018, at the start of a meeting with military leaders. (AP Photo/Susan Walsh)

President Donald Trump speaks in the Cabinet Room of the White House in Washington, Monday, April 9, 2018, at the start of a meeting with military leaders. (AP Photo/Susan Walsh)

United States Ambassador to the United Nations Nikki Haley speaks during a Security Council meeting at U.N. headquarters, Monday, April 9, 2018. (AP Photo/Seth Wenig)

In this photo released by the Syrian official news agency SANA, shows a bus carrying civilians who were released by the Army of Islam group that were held them since 2013, in Damascus, Syria, early Monday, April 9, 2018. Syrian state media is reporting that dozens of civilians who had been held for years by a rebel group near the capital Damascus have been freed. (SANA via AP)

United Nations Ambassador from Russia Vasily Nebenzya confers before a meeting of the U.N. Security Council, Monday April 9, 2018 at U.N. headquarters. (AP Photo/Bebeto Matthews)

White House press secretary Sarah Huckabee Sanders calls on a reporter during the daily briefing at the White House in Washington, Monday, April 9, 2018. Sanders was asked about Syria, Russia and other topics. (AP Photo/Susan Walsh)

In this photo released by the Syrian official news agency SANA, soldiers and residents salute civilians after they were released by the Army of Islam group that had held them since 2013, in Damascus, Syria, early Monday, April 9, 2018. Syrian state media is reporting that dozens of civilians who had been held for years by a rebel group near the capital Damascus have been freed. (SANA via AP)

In this photo released by the Syrian official news agency SANA, soldiers and residents salute civilians after they were released by the Army of Islam group that had held them since 2013, in Damascus, Syria, early Monday, April 9, 2018. Syrian state media is reporting that dozens of civilians who had been held for years by a rebel group near the capital Damascus have been freed. (SANA via AP)

President Donald Trump speaks during a cabinet meeting at the White House, Monday, April 9, 2018, in Washington. (AP Photo/Evan Vucci)

EDS NOTE: GRAPHIC CONTENT - This image released early Sunday, April 8, 2018 by the Syrian Civil Defense White Helmets, shows a rescue worker carrying a child following an alleged chemical weapons attack in the rebel-held town of Douma, near Damascus, Syria. Syrian rescuers and medics say a poison gas attack on Douma has killed at least 40 people. The Syrian government denied the allegations, which could not be independently verified. The alleged attack in the town of Douma occurred Saturday night amid a resumed offensive by Syrian government forces after the collapse of a truce. (Syrian Civil Defense White Helmets via AP)