President George W Bush secretly approved orders in July that for the first time allow American Special Operations forces to carry out ground assaults inside Pakistan without the prior approval of the Pakistani government, according to senior American officials.

The classified orders signal a watershed for the Bush administration after nearly seven years of trying to work with Pakistan to combat the Taliban and Al Qaeda , and after months of high-level stalemate about how to challenge the militants’ increasingly secure base in Pakistan’s tribal areas.

The stepped-up campaign inside Pakistan comes at a time when American-Pakistani relations have been fraying, and when anger is increasing within American intelligence agencies about ties between Pakistan’s ISI and militants in the tribal areas.

Analysts at the Central Intelligence Agency and other American spy and security agencies believe that not only the bombing of India’s embassy in Kabul in July by militants was aided by ISI operatives, but also that the highest levels of Pakistan’s security apparatus, including army chief Gen. Ashfaq Parvez Kayani, had knowledge of the plot.

“It’s very difficult to imagine he was not aware,” a senior American official said of General Kayani.

American intelligence agencies have said that senior Pakistani national security officials favour the use of militant groups to preserve Pakistan’s influence in the region, as a hedge against India and Afghanistan.

In fact, some American intelligence analysts believe that ISI operatives did not mind when their role in the July bombing in Kabul became known. “They didn’t cover their tracks very well,” a senior official said, “and I think the embassy bombing was the ISI drawing a line in the sand.”