DOVER AIR FORCE BASE — Four U.S. service members returned to American soil in flag-draped caskets on Wednesday after being killed in Iranian attacks in the Middle East.

The ceremony, known as a “dignified transfer” of the bodies, comes amid growing frustration with the U.S.-Israeli war with Iran.

The war has cost U.S. taxpayers at least $37.5 billion, has led to the deaths of 18 U.S. service members and injured more than 450 troops. It has killed thousands of Iranians.

Both Republican and Democratic lawmakers have raised questions about the war, which has boosted global oil prices and shows no signs of ending. Since the war started in February, President Donald Trump has offered differing objectives for the war.

The president traveled to Dover Air Force Base in Delaware for the ceremony.

“We’re going to honor them. For me it’s one of the hardest things to do as a president. But it has to be done,” Trump said before leaving for the ceremony. Asked what he would tell the families of the fallen, Trump said: “All I’m going to say is, we love you. We love your child, and that’s what they are to them. They’re their children. There’s no games, no nothing.”

U.S. presidents, vice presidents and dignitaries regularly attend the solemn transfer ceremonies at Dover — home of the largest U.S. military mortuary — during times of war or conflict.

The three U.S. service members killed when an Iranian missile hit their sleeping barracks at Muwaffaq Salti Air Base in Jordan on Friday were 1st Lt. Tyler James Feehan, 25, Sgt. Angel S. Rampersad, 28, and Pvt. Isabella Gonzales, 19. All three were assigned to U.S. Army air defense brigades.

The fourth death, of Sgt. Michael Emmanuel Swinton, 30, occurred on Sunday in a separate incident in Erbil, Iraq, during a controlled detonation of an attack drone.

The Pentagon said on Monday that 100 service members have been injured since July 7 and 96% have returned to duty.

Four in five Americans expect ‌the war to drag on for an extended period, according to a Reuters/Ipsos opinion poll conducted this month. Some 37% of respondents approved of U.S. military strikes against Iran.