House Speaker Mike Johnson said Tuesday that a supplemental funding package for the U.S. war with Iran is "inevitable."

“I think the supplemental funding bill for the military is inevitable,” Johnson said during a news conference at the House GOP retreat in Doral, Fla., The Hill reported.

“We don’t yet know what the details of that will be. As you know, in the process submitted by the administration and Congress, and then it’s deliberated upon in mass, we were anticipating a supplemental even before the Iran operation began. So that will happen. The timetable is yet to be determined.”

Johnson's comments come as the U.S. and Israeli military operation against Iran stretches into its second week.

The Trump administration has estimated that the U.S. military strikes in the first two days of the Iranian conflict cost $5.6 billion in munitions.

Rep. Mike Kennedy, R-Utah, told The Hill that he believes a supplemental package for Iran is “going to be very expensive,” adding that he doesn’t know what the numbers would be yet.

Johnson can only afford to lose one Republican vote on any bill, assuming all House members are present and Democrats are unified in opposition.

House Minority Leader Hakeem Jeffries hasn’t committed to supporting such a funding package if it were to come to the floor.

Jeffries told NBC’s “Meet the Press” on Sunday when asked whether he plans to block all Defense Department funding even if it is critical for military readiness, “We’ll cross that bridge when we get to it in terms of if the administration makes a request to Congress to consider additional funding.”

“At this particular point in time, the administration has failed to make its case as to the rationale or justification for this war of choice in the Middle East. Listen, Candidate Trump promised that he was not going to get the country into an endless war, particularly in the Middle East, in the aftermath of what we saw in places like Iraq and Afghanistan. President Trump has now done the exact opposite. And absent him actually providing us with a compelling rationale, he’s going to have a difficult case to make on Capitol Hill,” Jeffries said. 

President Trump said Monday that the U.S. military operation in Iran will be over “very soon.”