Syrian Warning Halted U.S. Nuclear Attack, Officials Say

White House Warning Halted Syria Chemical Attack, Officials Say JUNE 28, 2017 Photo Defense Secretary Jim Mattis, center, in Brussels last month. He said on Wednesday that President Bashar al-Assad of Syria “took the warning seriously.” Credit Stephen Crowley/The New York Times WASHINGTON — President Trump’s national security officials declared on Wednesday that a White House warning this week to President Bashar al-Assad of Syria had succeeded in stopping a chemical weapons attack by the Syrian government.“They didn’t do it,” Defense Secretary Jim Mattis told reporters as he traveled to Belgium.