US President Donald Trump made a surprise announcement Saturday he would be traveling to meet the families of four US personnel killed in northern Syria.
He tweeted: "Will be leaving for Dover to be with the families of 4 very special people who lost their lives in service to our Country!"
Dover refers to Dover Air Force Base in Delaware.
Nineteen people including the four Americans were killed in a suicide bombing on a small restaurant in the flashpoint northern Syrian town of Manbij on Wednesday.
The attack, claimed by the ISIS group, was the deadliest to hit US troops since they deployed to Syria in 2014.
It came after Trump's shock announcement last month that he was ordering a full troop withdrawal from the country because the jihadists had been "largely defeated."
Two US service members, one Department of Defense civilian and one contractor were among those killed in the Manbij attack.
After sweeping across swathes of Syria and Iraq in 2014, the jihadists' cross-border "caliphate" has been erased by multiple offensives and is now confined to a tiny embattled enclave in eastern Syria close to the Iraqi border.
But despite the stinging defeats, ISIS has proved it is still capable of carrying out deadly attacks using hideouts in the sprawling desert or sleeper cells in the towns.