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.

The all-caps post came hours after weekend bombings in Iran rattled oil markets and reignited fears of rising fuel costs.

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.

Iran retaliated Monday for the U.S. attacks on its nuclear sites by targeting Al Udeid Air Base, a sprawling desert facility in Qatar that serves as a main regional military hub for American forces. President Donald Trump said in a social media post that no Americans were harmed and “hardly any damage was done.

It remained to be seen whether the attack would ignite a regional war or provide the U.S. and Iran with an off-ramp from their intensifying confrontation.