In a subsequent statement Pompeo said
The Saudis were the nation that was attacked. It was on their soil. It was an act of war against them directly.
So the interpretation given by some of the pundits was that the US is expecting the Saudis to lead in any military response. Trump himself made a statement that received similar commentary:
For his part, Trump has made clear he wants the Saudis to take the lead in any response since it was an attack on their soil. "We have to sit down with the Saudis and work something out," he told reporters on Tuesday. "That was an attack on Saudi Arabia, and that wasn't an attack on us." [...]
Kirsten Fontenrose, a former director of the Persian Gulf region on Trump's National Security Council, said that since the White House already knows where the Saudis stand, it may be planning to use the kingdom to give it cover for not taking military action. "This gives him [Trump] a way out to not push for kinetic action," Fontenrose said.
For a lot more commentary on the entire situation, see the BBC article posted a few minutes ago. It covers a lot of "what ifs", too many to go over here. The bottom line of that is: we don't yet have any clear indication what the US is going to do militarily in response to this attack.
If there's a quote from Trump that summarizes his position insofar it's probably this from yesterday (Wednesday 18th):
“There are many options. There’s the ultimate option and there are options that are a lot less than that. And we’ll see,” Trump told reporters in Los Angeles.
“I’m saying the ultimate option meaning go in – war,” he added.