Two senior Republican senators called on Monday for a thorough review of US relations with Pakistan, declaring that all security and economic aid to Islamabad must be reconsidered.
John McCain and Lindsey Graham -- influential members of the Senate Armed Services committee -- said Washington had to be realistic about the deteriorating relationship.
They said actions of Pakistan's military, such as its support for militant groups, were harming US forces and threatening American security.
"The time has come for the United States to fully review its relations with Pakistan," McCain and Graham said in a statement. "In particular, all options regarding US security and economic assistance to Pakistan must be on the table, including substantial reductions and stricter standards for performance."
McCain was the Republican party's candidate in the 2008 presidential election won by Democrat Barack Obama.
The United States has allocated some $20 billion in security and economic aid to Pakistan since 2001, much of it in the form of reimbursements for assistance in fighting militants.
A November 26 Nato air strike that killed 24 Pakistani troops on the border with Afghanistan has provoked the latest crisis in relations between the two nations. Relations were already frayed after the secret US raid in May that killed al Qaeda leader Osama bin Laden in a Pakistani town.
The frustration with Pakistan expressed by McCain and Graham is widespread on Capitol Hill.
This year committees in both the House and Senate have voted in favor of making economic as well as security aid to Islamabad conditional on its cooperation in fighting militants such as the Haqqani network, which Washington blamed for an attack on its embassy in Kabul in September.
Final decisions on US aid for 2012 may be made in the coming weeks as Congress tries to finish its appropriations bills for 2012.