President Donald Trump’s new national security adviser enters the White House this week facing an immediate test in developing a response to a suspected chemical-weapons attack in Syria that has killed dozens.
John Bolton, who has served as American ambassador to the United Nations, State Department official under two presidents, and a Fox News commentator, is known for advocating muscular military responses to advance U.S. interests and will play a key role in helping Mr. Trump decide whether to strike Syrian President Bashar...