Pakistan army chief General Ashfaq Kayani chaired an emergency meeting with his top commanders Sunday as a war of words with the United States escalated.

Pakistani officials said corps commanders met at the General Headquarters in Rawalpindi to review the prevailing security situation in the country.

The meeting followed scathing U.S. allegations that the Pakistani spy agency, the ISI, is assisting the al-Qaida-linked Haqqani network to attack U.S. targets in neighboring Afghanistan.

The outgoing chairman of the U.S. Joint Chief of Staffs, Admiral Mike Mullen, told a Senate hearing last week that the Haqqani network acts as a "veritable arm" of the ISI, and its fighters planned and conducted this month's assault on the U.S. embassy in Kabul and on NATO bases in Afghanistan.

Pakistani officials have rejected the allegations as baseless, warning they are detrimental to regional peace efforts.

In Washington Sunday, a member of the Senate Armed Services Committee said "the sovereign nation of Pakistan is engaging in hostile acts against the U.S. and Afghanistan that must cease."  Republican Senator Lindsey Graham of South Carolina told Fox News Sunday Haqqani militants are killing American soldiers.  He said that if Pakistan's intelligence continues to embrace terrorism as a national strategy, Washington will have to put all options on the table, including defending U.S. troops.

Pakistani Interior Minister Rehman Malik insisted Sunday that the Haqqani network is not operating from Pakistan.  He alleged the network was established and trained by the American CIA with support from Pakistan to fight the Soviet occupation of Afghanistan in the 1980s.

Malik reiterated that Pakistan is cooperating with the U.S. in its fight against terrorism, and that he has ordered authorities to tighten border controls between Afghanistan and Pakistan.

The U.S. and Pakistan are allies in the war against militants in Afghanistan.  But in light of the recent allegations, Pakistan has warned the U.S. that it risks losing an ally.

Meanwhile, the head of U.S. Central Command, General James Mattis, met with Pakistani leaders and emphasized the need for persistent engagements among militaries of the U.S., Pakistan, and other countries in the region.

A Pakistan army statement says a Pakistani representative in the talks, Khalid Shameem Wyne, expressed concern about the negative statements emanating from Washington and stressed the need to address the irritants in the relationship which are "the result of an extremely complex situation.”

Some information for this report was provided by AP, AFP and Reuters.