President Donald Trump marked Memorial Day at Arlington National Cemetery by honoring 13 U.S. service members killed in the Iran war.

He said their deaths were part of efforts to prevent Iran from obtaining a nuclear weapon, a goal he reaffirmed during the ceremony.

Trump noted ongoing negotiations with Iran and said progress was being made toward a possible ceasefire or peace deal, though he stressed no agreement would be rushed.

The Iran conflict, now nearing three months, has caused significant economic disruption and remains unpopular with many Americans, according to polling, USA Today has reported.

Senior U.S. military and government officials joined Trump at the ceremony as talks over the war’s resolution continue.