Trump said in a social media post after the attack on Al Udeid Air Base that he wanted Iran to move toward peace talks and that he would encourage Israel to do the same.

European nations worked Monday to keep diplomatic efforts to curb the Israel-Iran war alive as the two countries traded strikes following the United States’ weekend attack on Iran’s nuclear program. Calls for Tehran to enter talks with Washington appeared to fall on deaf ears as it reached out to ally Russia for support.

F.B.I. and D.H.S. officials cautioned state and local law enforcement of the possibility of threats to U.S. communities.