The White House is calling on Pakistan to do more to fight terrorism and says that it will announce "specific actions" within days to pressure Islamabad.
"We know that they can do more to stop terrorism and we want them to do that," White House spokeswoman Sarah Sanders said on January 2, adding that further action will be announced within 48 hours.
Reuters quoted congressional sources on January 3 as saying the announcement could come later that day or on January 4.
The news agency cited two congressional aides as saying the U.S. administration has been informing members of Congress that it will announce plans to cut off "security assistance" to Pakistan, although it was not clear how much or what type of assistance would be cut or for how long.
The White House warning came after the U.S. ambassador to the United Nations, Nikki Haley, told reporters in New York that "there are clear reasons" for the Trump administration to withhold $255 million in assistance to Pakistan.
"Pakistan has played a double game for years," Haley said. "They work with us at times, and they also harbor the terrorists that attack our troops in Afghanistan. That game is not acceptable to this administration."
Pakistani UN Ambassador Maleeha Lodhi responded that her country's fight against terrorism is not based on any consideration of aid but on national interests and principles.
"We have contributed and sacrificed the most in fighting international terrorism and carried out the largest counterterrorism operation anywhere in the world" in Pakistan's tribal regions, Lodhi said.
Earlier on January 2, Pakistan and Washington traded charges over Islamabad's record on pursuing terrorists, with Pakistan criticizing a Twitter post by President Donald Trump that threatened to cut of billions of dollars in aid and accused Islamabad of "lies and deceit" and providing a safe haven for terrorists.
Pakistan's National Security Committee, a body that deals with defense issues, said the U.S. criticism stemmed from Washington's failure to win its 16-year war against the Taliban in Afghanistan and that Pakistan "cannot be held responsible for the collective failure in Afghanistan."
The statement said "blaming allies certainly does not serve the shared objective of achieving lasting peace in Afghanistan and the region."
Meanwhile, Prime Minister Shahid Khaqan Abbasi's office said Islamabad will remain committed to playing a constructive role toward an Afghan-led and Afghan-owned peace process despite "unwarranted allegations."
The prime minister's statement said the real challenges in Afghanistan were political infighting, massive corruption, phenomenal growth of drug production, and the expansion of ungoverned spaces inside Afghanistan full of sanctuaries for multiple international terrorist organizations that pose a direct threat to Afghanistan, its neighbors, and the region.
Earlier on January 2, Pakistan summoned U.S. Ambassador David Hale in response to Trump's January 1 Twitter message and accused the United States of "mistrust."
Trump's tweet, his first of 2018, said that the United States had "foolishly" given Pakistan more than $33 billion in aid over the last 15 years, "and they have given us nothing but lies & deceit, thinking of our leaders as fools."
The White House confirmed it would continue to withhold $255 million in military aid to Pakistan out of frustration over what it has characterized as Islamabad's refusal to confront terrorist networks.
The administration first started a "temporary withholding" of the funds, part of a $1.1 billion aid package authorized in 2016 by Congress, in August.
Pakistani Defense Minister Khurram Dastgir Khan returned criticism in a tweet noting that Islamabad "as anti-terror ally has given free to US: land & air communication, military bases & intel cooperation that decimated Al-Qaeda over last 16yrs, but [the United States has] given us nothing but invective & mistrust."
Foreign Minister Khawaja Mohammad Asif told Pakistan's Urdu-language Geo Television that "the United States should hold its own people accountable for its failures in Afghanistan."
"America is frustrated over defeat in Afghanistan. America should take the path of dialogue instead of using military might in Afghanistan," Asif said.
Asif added that all financial aid from the United States had been "properly audited" and that "services [were] rendered."
The Afghan ambassador to the United States, Hamdullah Mohib, welcomed Trump's tweet.
Pakistan "receives funds from the United States to fight against terrorists, but it has not destroyed terrorist safe havens from where terrorists continuously carry out attacks in Afghanistan," he told RFE/RL on January 1.
[Trump's tweet] is a positive message for us, should U.S. pressure on Pakistan increase," Mohib added. "If the funds that Pakistan receives from the U.S. are cut off, this can exert direct pressure on Pakistan and we welcome this effort."
However, China gave Islamabad its backing, with Foreign Ministry spokesman Geng Shuang saying that Pakistan "has made a prominent contribution to global antiterror efforts."
"The international community should fully recognize this," he added.
Trump and U.S. Vice President Mike Pence have in the past accused Islamabad of supporting terrorist groups and have demanded that Pakistan act against the Taliban and Haqqani network.
The frequency of suspected U.S. drone attacks near the Pakistani-Afghan border has increased notably since Trump introduced his Afghanistan strategy in August.
With reporting by Reuters, AP, AFP, and Dawn