His trip to Dover coincided with a turbulent day in Washington, as protesters assembled on the National Mall for a women's march and Trump prepared for an announcement from the White House aimed at resolving a budget battle over his demands for billions of dollars to erect a wall along the southern border - an impasse that has caused a government shutdown and left hundreds of thousands of federal workers without pay.
Before the short flight to Delaware, Trump repeated disputed claims to have essentially rid Syria of Islamic State fighters, saying that "when I took over, Syria was loaded with ISIS" but "we've brought it down to less than 1 percent." In fact, the territory controlled by the Islamic State had been substantially reduced before Trump took office, though experts say the terrorist group still has dangerous capabilities.
Trump depicted this week's attack, which targeted a restaurant frequented by Americans in the northern city of Manbij, as one that was carried out by remnants of an otherwise spent terrorist group. Though defeated, he said, "that doesn't mean you're not going to have somebody around" capable of violence.
His assertions and determination to pull U.S. forces and advisers from Syria are at odds with officials in his administration who have led that effort. Former defense secretary Jim Mattis resigned in disagreement with Trump's Syria plan.
Brett McGurk, who served as the special presidential envoy to the coalition to counter the Islamic State, also resigned in protest and said in an opinion column published in The Washington Post Friday that Trump's decisions were "giving the Islamic State - and other American adversaries - new life."
The Pentagon identified three of those killed Wednesday as Army Chief Warrant Officer 2 Jonathan Farmer; Navy Chief Cryptologic Technician Shannon Kent; and civilian Scott Wirtz, a former Navy SEAL working for the Defense Intelligence Agency.
The fourth individual, who worked for a defense contractor, was identified as Ghadir Taher.
A suicide bomber detonated an explosive vest at the restaurant where the Americans had gathered after a meeting with local military officials. Three U.S. troops were also wounded in the attack, the deadliest against U.S. forces in Syria since their entry into the country in 2015.
Earlier this week, Trump derailed plans by House Speaker Nancy Pelosi, D-Calif., and other lawmakers to visit U.S. forces in Afghanistan, denying them access to U.S. government aircraft.