NAVAL AIR WEAPONS STATION CHINA LAKE, Calif. — Defense Secretary Ash Carter said Tuesday that the administration will stick to its request of $59 billion in war funding next year set under a 2015 bipartisan budget deal, but signaled he is also open to spending more. 

Carter on Tuesday previewed the administration’s $582 billion defense budget request, which would have a base budget of $524 billion and a war funding budget, also known as overseas contingency operations (OCO), of about $59 billion.

{mosads}Those levels for defense funding were set under the 2015 Bipartisan Budget Act, but some Republican defense hawks in Congress say the $59 billion should be a floor, not a ceiling, given increased spending in the war against the Islamic State in Iraq and Syria (ISIS) and to bolster European allies amid Russian aggression.

“Yes, there’s a number set in the bipartisan budget agreement. We respect that, but, and this is an important but, OCO is by definition a variable fund that depends on what you do in the course of a year,” Carter told reporters during a trip to Naval Air Weapons Station China Lake in California.  

However, Carter also added, “We asked for the amount that we think we’ll need.” 

He noted that he could go back to Congress and ask for more funding for OCO, which was created for unforeseeable contingencies and not subjected to budget caps unlike the base defense budget. 

“I would think that if we need more, they would respect that as well,” he said. 

House Armed Services Committee Chairman Mac Thornberry (R-Texas) earlier Tuesday said the budget request did not account for a 50-percent increase in spending for the war against ISIS from last year, or a quadrupling of funds to reassure European allies worried about Russia. 

“The increase in counter-ISIS investments and deterrence of Russia are welcome and needed moves,” Thornberry said in a statement. “But the president’s budget request, for example, does not add funds to accommodate the $7.5 billion in additional funding to counter ISIS or the $3.4 billion to deter Russia.” 

Carter said the amount did account for both, adding that it could later be adjusted.

“Some years the Department of Defense has ended up spending more than it had originally asked for…sometimes it has ended up spending less, and we’ve given back money to the Treasury as a consequence — that’s in the nature of not knowing exactly,” he said. 

“There will be some things that we don’t see in front of us, and we’ll have to adjust,” he said.