The Senate will soon take up a Defense spending bill that would cut nearly $2.5 billion in military aid to foreign fighting forces, an unusually large budget subtraction some say reflects a fundamental change in lawmakers’ security priorities. 

At issue is the $675 billion fiscal 2019 Defense money bill, which Senate Appropriations approved late last month and which the chamber may take up later this month. 

The measure would downsize President Donald Trump’s requests for programs that equip or train militaries and militias that are combating terrorists on America’s behalf in Afghanistan, Pakistan, Iraq, Syria and beyond. Some of the proposed cuts are reductions to the president’s fiscal 2019 budget request, and some are so-called rescissions of fiscal 2018 funding that hasn’t yet been spent.

The nearly $2.5 billion in recommended cuts is one of the largest changes to any category of defense spending in either the Senate’s Pentagon appropriations bill or the House’s, and it would stand out as one of the heftiest reductions to any single category of defense programs in recent memory, analysts said.

“It’s an unusually large amount to cut,” said Mark Cancian, a defense budget expert with the Center for Strategic and International Studies.

Watch: Lawmakers Press Pompeo On Syria Response Without Congressional Approval

Because the Senate is considering cutting fully $1.9 billion more from such programs than the House-passed bill, this is shaping up as one of the biggest discrepancies that must be reconciled before a final Pentagon spending bill can be written.  

The House and Senate differences over military aid have to be sorted out in the context of a broader disagreement over how much to reorder the president’s budget request. 

Specifically, the Senate bill would allocate about $8.6 billion more than Trump proposed for developing and procuring weapons. By comparison, the House would add much less for investments in research and procurement spending — just over $2.6 billion more than Trump wanted.

Senate appropriators and authorizers have been more vocal than their House counterparts in arguing that Trump’s budget does not reorient Pentagon programs decisively enough away from combat against al Qaida and the Islamic State and instead toward more rapid modernization of the U.S. arsenal to prepare for fighting nations that wield cutting-edge military forces. 

The Senate appropriators’ reductions to military aid programs do not appear to represent a withdrawal of congressional support for counterterrorism missions, so much as a reduction in their priority relative to other increasingly pressing goals, experts say.

The Senate bill “reflects a change in priorities from counterterrorism to conflicts with great powers like Russia and China,” Cancian said.

Senate aides agree that reducing spending on military aid programs will free up more money to modernize U.S. weaponry, but they contend that the aid cuts would have occurred anyway, mainly because the president requested more money for those programs than they need. 

The nearly $2.5 billion in Senate Appropriations cuts to military aid would come in four major programs:

Coalition Support Fund. This account reimburses U.S. allies, mainly Pakistan, for their costs in fighting terrorism. 

Since fiscal 2015, defense authorization acts have required the administration to certify that Pakistan is helping, instead of hurting, the fight against terrorism before such funds are spent. Those certifications have not been made, and Trump announced in January that he is ceasing most military aid to Pakistan. 

As a result, large sums of Coalition Support Fund appropriations are as yet unspent. So Senate appropriators are rescinding the $800 million appropriation for fiscal 2018. Their House counterparts want to rescind only $350 million of it.

Afghanistan Security Forces Fund. In addition, the Senate plan would reduce the president’s fiscal 2019 request for the Afghanistan Security Forces Fund, money to train and equip that country’s military and police. The Senate bill would subtract $533 million from the fund, decreasing it from $5.2 billion down to the current level of spending, which is $4.7 billion. 

The Senate panel’s stated reason for the decision: The Pentagon has not adequately detailed how the Afghanistan program’s money has been spent to date. The House, by comparison, makes no such cuts.

Countering ISIS. The third area of proposed Senate cuts would occur in the so-called Counter ISIS Train and Equip Fund, which bankrolls forces in Syria and Iraq fighting the Islamic State, or ISIS. 

U.S. and coalition forces have pushed the group out of most of its territory in those countries, though about 1,000 square miles reportedly remains in the group’s hands. 

The Senate panel would cut $406 million out of the administration’s $1.4 billion request for the anti-ISIS program. The House would reduce the same program by just $25 million.

More than half of the Senate’s proposed fiscal 2019 cut, or $250 million, is just a bookkeeping shift of funds from one part of the budget to another, aides said. But the rest of the Senate cuts in the counter-ISIS program are, like the cuts to the Afghanistan aid, due to the Pentagon’s failure to fully explain its spending, the Senate report said.

The Senate committee also took back $400 million from the anti-ISIS fund’s fiscal 2018 appropriation, a move the House did not make.

Military sales. The final set of reductions to military aid would take place in the budget for the Defense Security Cooperation Agency, which finances sales of U.S. military equipment to allies. Under the Senate bill, the president’s fiscal 2019 request for that agency would drop $200 million, and another $150 million in fiscal 2018 money would be subtracted.

The reason, aides said: The agency has not been able to spend all the money it has received for several years running. 

The House committee decreased the defense security agency’s proposed budget by a net $243 million. The House report said the cut occurred partly because some programs had been transferred out of the agency’s budget and partly because House appropriators decided to subtract some $93 million from the Southeast Asia Maritime Security Initiative, a program that provides assistance to allies in the Asia-Pacific region.

The military aid programs are funded in the Overseas Contingency Operations section of the budget. That budget would total just under $68 billion in the Senate bill, or nearly the same level as the request, despite the cuts to military aid and other OCO programs.

The Senate panel was able to essentially fully fund the OCO request because it provided more money in the OCO account by shifting about $3.4 billion from the base budget’s operations and maintenance accounts to the war budget’s similar accounts. 

That $3.4 billion was not all that was taken out of the base budget’s operations accounts. All told, nearly $5.5 billion was subtracted from the $199.5 billion request for operations spending in the base budget. 

Subtracting that $5.5 billion from the base budget’s operations account — and taking another $1.4 billion from the personnel account — provided the bulk of the funds the committee needed to pay for $8.6 billion above the requested amounts for researching and procuring weapons and other gear. 

The Senate panel wants to spend much of that $8.6 billion on fighter jets, warships, anti-missile interceptors and a National Guard equipment fund, all programs that are also House priorities. 

But the Senate panel said that it focused nearly half of that additional modernization money, or about $3.8 billion, on seven next-generation programs: hypersonics, space, cyber, artificial intelligence, microelectronics, lasers and improved testing ranges for new weapons. 

Senate appropriators and authorizers alike are concerned that the rhetoric of the administration’s National Defense Strategy about moving to some degree away from counterterrorism and toward competition against major powers was not matched by enough changes in the fiscal 2019 budget request.

“While the NDS recognizes the persistent nature of terrorist threats and the need to counter those threats, it also represents a significant shift toward long-term, strategic competition and operations in contested domains,” the Senate Appropriations report said.

When Senate Appropriations passed its bill, Chairman Richard C. Shelby of Alabama said the seven cutting-edge technologies that netted $3.8 billion in unrequested funds will be needed “to defend our nation in an increasingly complex and competitive national security environment.”

The White House has scaled back foreign aid budgets, but when it comes to military aid in particular, administration officials have given no signals that they approve of cuts.

The White House has yet to issue a Statement of Administration Policy on the Senate’s defense spending bill, but in the White House statement on the Senate authorization bill, Trump’s aides strongly opposed provisions that would merely withhold, but not cut, some anti-ISIS funding, pending submission to Congress of reports on the conflict. 

“Restrictions on or gaps in funds that underpin the U.S. strategy of defeating ISIS by, with, and through partner forces — including the vetted Syrian Democratic Forces — would impede our ability to secure a lasting defeat of ISIS in Iraq and Syria and would limit the Secretary of Defense’s ability to act in the national security interest of the United States,” the White House statement said.

Asked for the Pentagon’s reaction to the proposed cuts to foreign military aid, Army Lt. Col. Michelle Baldanza, a spokeswoman, said, “I am not going to be able to provide comment on pending legislation.”

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