The US has been pushing Pakistan to crack down on militant safe havens in the country, and had suspended hundreds of millions of dollars in security assistance to Islamabad at the beginning of the year.

"Due to a lack of Pakistani decisive actions in support of the South Asia Strategy... $300M (actually $323.6M to include non-Pakistan funds) was reprogrammed by (the Defense Department) in the June/July 2018 time frame for other urgent priorities," Lieutenant Colonel Kone Faulkner said in an email to AFP.

The Defense Department "is awaiting congressional determination on whether this reprogramming request will be approved or denied," Faulkner said.

Pakistan has fought fierce campaigns against some militant Islamist groups that threatened its own security.

But US officials accuse Pakistani officials of ignoring or even collaborating with groups that launch operations into Afghanistan from safe havens along the countries' border.

These groups threaten the US-backed Afghan government and have attacked and killed many of the American troops that were sent there after the September 11, 2001 attacks.

"We continue to press Pakistan to indiscriminately target all terrorist groups," Faulkner said.