WASHINGTON (AP) — President Donald Trump will undertake one of the most solemn duties facing the commander in chief on Wednesday when he will witness the dignified transfer of two Iowa National Guard members killed in an attack in the Syrian desert.

The ritual at Dover Air Force Base in Delaware honors U.S. service members killed in action. Trump, who traveled to Dover several times in his first term, once described it as “the toughest thing I have to do” as president.

The two guardsmen killed in Syria on Saturday were Sgt. Edgar Brian Torres-Tovar, 25, of Des Moines, and Sgt. William Nathaniel Howard, 29, of Marshalltown, according to the U.S. Army. Both were members of the 1st Squadron, 113th Cavalry Regiment, and have been hailed as heroes by the Iowa National Guard.

A U.S. civilian working as an interpreter, identified as Ayad Mansoor Sakat of Macomb, Michigan, was also killed in the attack. Three other members of the Iowa National Guard were injured, though their identities have not been disclosed by the Pentagon.

During the process at Dover, transfer cases draped with the American flag carrying the remains of the fallen soldiers are brought from military aircraft to an awaiting vehicle, which then transports them to the base's mortuary facility for preparation for their final resting place.

Trump expressed his mourning over the soldiers' deaths and vowed retaliation. This attack comes amid a thawing relationship between the U.S. and Syria, as the latter has become part of a coalition fighting the Islamic State.

The President has developed a relationship with interim Syrian President Ahmed al-Sharaa, who previously led an Islamic insurgent group. Trump reiterated that the attack did not involve al-Sharaa, who he stated was devastated by the incident.

Throughout his presidency, Trump has honored U.S. military personnel at Dover, reflecting on the ever-present sacrifices of those serving overseas.