The US will respond "in a manner of our choosing" after three American troops were killed and at least 34 injured in a drone strike in Jordan, its National Security Council spokesman has said.
John Kirby would not reveal what options are being discussed in the White House, but promised a response to Saturday night's attack near the Syrian border.
Speaking on NBC's Today programme, he said: "I'm not going to get ahead of the president's decision space here or talk about what the options might be.
"He said we'll respond. We absolutely will do it at a time or in a manner of our choosing. Certainly.
"We're taking a look, real hard, at what the options need to be for a response."
The attack caused the first US fatalities after a long period of strikes by such groups against American forces in the Middle East.
The American base, known as Tower 22, sits near the demilitarised zone on the border between Jordan and Syria.
The small installation includes American engineering, aviation, logistics and security troops with about 350 US Army and Air Force personnel deployed there.
On the potential of a conflict with Iran, Mr Kirby said: "We've communicated directly to Iran what we expect to see.
"What we want is a stable, secure, prosperous Middle East, and we want these attacks to stop.
"That means we've got options here ahead of us and we're going to have to work our way through that."
Meanwhile, negotiators from Israel, the US, Egypt and Qatar are said to have agreed on a framework for the release of the remaining Hamas hostages, NBC News has reported.
More than 100 hostages remain captive after the 7 October attack on Israel by Hamas fighters.
Mr Kirby told CNN how securing the release of the hostages could help increase the passage for more aid to Gaza.
"That could really make a difference in terms of getting more hostages out, getting more aid in and actually getting the violence to come down," Mr Kirby said of the potential deal, which is expected to be presented to Hamas in the coming hours.
"We feel pretty good about the discussions and where they're going and the promise of something potentially pretty significant."