The president had opposed Israeli action against Iran but came to believe that Israel had reason to act and that the U.S. would have to lend some support.

President Donald Trump is attending the opening day of the Group of Seven summit in Canada on Monday, where some of the staunchest and oldest U.S. allies are expected to discuss tariffs and the escalating military conflict between Israel and Iran — all while attempting to avoid direct confrontations with the mercurial U.