The weekend attacks on Kabul, blamed by the US on the Pakistan-linked Haqqani network, will strengthen Washington's hand in talks with Islamabad over drone strikes and NATO supply routes, analysts say.
The US ambassador to Afghanistan Ryan Crocker said Thursday the attacks -- the biggest to hit the Afghan capital in 10 years of war -- were planned by Haqqani leaders in North Waziristan.
US Secretary of State Hilary Clinton said Washington will continue to urge Pakistan to "squeeze" the Haqqani network, comments echoed by Crocker, who said the US was "pressing the Pakistanis very hard" for action against the militants.
A senior official with ISI, told AFP that after what happened in Kabul this kind of pressure from Washington was expected.
"Our apprehension right from the beginning has been that the US will use the Kabul attacks as a pretext to resume drone strikes with increased vigour, put pressure on Pakistan to launch operations in North Waziristan and re-open the NATO supply route," the official said.
Islamabad and Washington are trying to patch up a fractured relationship that lurched from crisis to crisis last year and reached a low after a US air strike inadvertently killed 24 Pakistani soldiers at a border post in November.
Pakistan closed its border to convoys supplying NATO troops in Afghanistan in response to that incident and a parliamentary review of ties last week called for an end to US drone strikes within Pakistani territory.
Analysts say the Kabul attacks give the US greater scope to lean on Pakistan in talks to reopen the supply lines and continue drone strikes.
"The US pressure can increase in future both in terms of re-opening NATO supplies or taking action against the Haqqanis," security analyst Hasan Askari said.
"Re-opening of the supply route is the top and foremost priority for the US. If Pakistan does not re-open the supply route, then they will exert all sorts of pressures."
Islamabad denies any support for Haqqani activities, but former US military chief Admiral Mike Mullen has described the network as a "veritable arm" of the ISI.
The United States blames the Haqqanis, who are closely affiliated with the Taliban, for fuelling the 10-year insurgency in Afghanistan, attacking US-led NATO troops and working to destabilise the Western-backed government of Afghan President Hamid Karzai.
Washington significantly stepped up demands last year on Pakistan to take action against the network, which it blames for a series of attacks including a 19-hour siege of the American embassy in Kabul on September 13.
But Pakistan's military says it is overstretched fighting local Taliban to launch an offensive against the Haqqanis in North Waziristan, a stronghold of Taliban and Al-Qaeda linked militants.
"There is no question of any new military offensive in North Waziristan as our troops are currently engaged in consolidating the gains in other northwestern and tribal regions, where operations were earlier conducted," the ISI official said.
Drone strikes are resented in Pakistan as violations of sovereignty, despite the fact that they have at times worked in Islamabad's favour, such as when they killed Pakistani Taliban founder Baitullah Mehsud in August 2009.
"Pakistan's position on drone strikes is very clear -- we will not allow any drone strikes in future," the ISI official said.
"We are capable of doing it by ourselves. They should tell us the target and we can successfully neutralise it."
But analyst Imtiaz Gul, who has written several books on Afghanistan, said there was no chance of the US giving up the drone campaign, which it regards as a highly effective tool in the fight against Al-Qaeda-linked militants.
"We should not be under any illusion that Americans will stop drone attacks or the CIA will stop pursuing Al-Qaeda targets," he said.
"Once formal talks resume between Pakistan and the US on the resumption of NATO supplies and other issues, the US may alter the modus operandi by creating a facade of joint ownership for drone attacks."