Pakistan has received more than $33 billion in U.S. assistance since 2002, including more than $14 billion in so-called Coalition Support Funds (CSF), a U.S. Defense Department program to reimburse allies that have incurred costs in supporting counter-insurgency operations.
It is an important form of foreign currency for the nuclear-armed country and one that is getting particularly close scrutiny during the Trump administration review.
Last year, the Pentagon decided not to pay Pakistan $300 million in CSF funding after then-U.S. Secretary of Defense Ash Carter declined to sign authorization that Pakistan was taking adequate action against the Haqqani network.
U.S. officials said the Trump administration was discussing withholding at least some assistance to Pakistan.
Curtis' report also singled out the aid as a target.
But U.S. aid cuts could cede even more influence to China, which already has committed nearly $60 billion in investments in Pakistan.
Another option under review is broadening a drone campaign to penetrate deeper into Pakistan to target Haqqani fighters and other militants blamed for attacks in Afghanistan, U.S. officials and a Pakistan expert said.
"Now the Americans (will be) saying, you aren't taking out our enemies, so therefore we are taking them out ourselves," the Pakistan expert, who declined to be identified, said.
Pakistan's Chief of Army Staff, General Qamar Javed Bajwa last week criticized "unilateral actions" such as drone strikes as "counterproductive and against (the) spirit of ongoing cooperation and intelligence sharing being diligently undertaken by Pakistan".