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 U.S. government is warning travelers to prepare for closed airspace in the Middle East and potential demonstrations against Americans.

President Donald Trump’s decision to strike nuclear sites in Iran on June 21 drew both praise and rebuke as the United States crept further into the war between Israel and Iran. Iran retaliated on June 23 by launching missiles at a U.S. military base in Qatar, sparking fears of further action, including on U.S. soil.

In retaliation for U.S. military attacks against Iran, the country could attempt to shut down the Strait of Hormuz, through which one-fifth of the world's oil supply is shipped each day