Bitter disputes over covert CIA activities and drone attacks inside Pakistan, lack of progress over peace talks in Afghanistan, and rising Islamist-led opposition to the presence of foreign forces in the region are fuelling the biggest crisis in US-Pakistan relations since the 9/11 attacks, Pakistani politicians, army sources and intelligence officers say.
Pakistan is seen by Washington and London as a vital ally in the "war on terror", while the Pakistani government and army say they remain committed partners 10 years after the Afghan conflict began.
But harsh US criticism of Islamabad's counter-terrorism campaigns in Pakistan's western tribal areas, repeated in a White House report last week, and "blowback" from the US military surge in Afghanistan are testing the relationship to breaking point, officials warn.
"We will not accept the stigmatising of Pakistan," said Salman Bashir, Pakistan's foreign secretary. "We need to re-examine the fundamentals of our relationship with the United States to get greater clarity. There has been a pause. Now we must start again."