Pakistan's military offensive against the Taliban in the Swat valley has done nothing to allay Indian doubts about its willingness to crack down more widely on Islamist militants, analysts say.
That leaves both countries vulnerable to a flare-up of tensions still simmering after last November's attack on Mumbai which could torpedo the US administration's plans for Afghanistan and Pakistan.
It also complicates US efforts to coax Pakistan into moving troops from its eastern border with India to fight the Taliban on its western border with Afghanistan.
Gurmeet Kanwal at the Centre for Land Warfare Studies in New Delhi said he believed the Pakistan Army considered the Taliban, especially the Afghan Taliban, to be a strategic asset "and has no intentions whatsoever of fighting them".
"Meanwhile, the army will continue to 'stage' operations ... selectively
to 'show' that serious attention is being given to fighting the war on terror," he said.
India has long accused Pakistan of nurturing Islamist militancy to expand its influence in the region, either in Afghanistan through the Afghan Taliban or through militant groups based in its Punjab province used to fight in Kashmir.
Indian analysts argue that it will selectively target groups such as the militants in the Swat valley to ease US pressure while leaving so-called 'anti-India' assets alone.
Pakistan -- in the difficult position of not being able to announce publicly a change of policy without acknowledging activities it denied in the past -- insists it is also being targeted by the militants and is determined to stop them.
Any apparent hesitation, it says, was more to do with a desire to avoid civilian casualties and the difficulty of fighting an enemy within that does not wear a uniform.
"If we lose this war, we will lose because of the killing of innocent people," said a Pakistani diplomat.
"The army is perfectly serious about taking on the Taliban," said Brian Cloughley, a specialist in the Pakistan Army. He said about 1,800 soldiers had been killed fighting the Taliban over the past four years. "Every casualty the army takes makes them even more determined to get on with the job."
New Indian Government
The differences between the two countries had slipped into the background because of India's long election campaign but will come to the fore with the Congress party now re-elected.
In particular, India is expected to face US pressure to resume peace talks it broke off after blaming the Pakistan-based Lashkar-e-Taiba militant group for the Mumbai attack.
Pakistan's High Commissioner to Britain, Wajid Shamsul Hasan, said Pakistan had suffered too from the fall-out of Mumbai and that peace talks to resolve the long-running dispute over Kashmir would help undercut support for militants.
"Pakistan wants to re-engage in the composite dialogue."
Prime Minister Manmohan Singh, expected to remain in office after the Congress election victory, this month ruled out talks. But even if India were to reopen dialogue, the mood after Mumbai leaves little room for progress on Kashmir, analysts say.
India rejects any outside mediation on Kashmir, which it sees as a bilateral matter. But nor can Washington afford to leave the relationship between India and Pakistan to fester.
The biggest risk is obviously of a fresh attack meant to provoke Indian retaliatory strikes on Pakistan which would take pressure off militants on the Afghan border.
"That's probably the nightmare scenario," said Shuja Nawaz at the Atlantic Council of the United States.
But even simply worrying about Indian retaliation is enough to stop the Pakistan Army from moving large numbers of troops away from the Indian border -- all the more so after the Indian military developed a 'Cold Start' doctrine to help it mobilise quickly for lightning strikes.
Nawaz said an army division had been brought back from Pakistan's tribal areas after the Mumbai attack. Another division had since been sent in, along with an extra brigade.
But that would give a net increase in the tribal areas of barely 5,000 or 6,000 troops -- a fraction of Pakistan's 600,000 to 700,000-strong army.
And with India unwilling to pull back its own troops from the Line of Control dividing Kashmir -- fearing this would allow militants to infiltrate from Pakistan -- both militaries appear to be as stalemated as ever.
A common enemy
So, is there any room at all for compromise?
The two countries are poles apart on their views on each other's roles in Afghanistan. Islamabad believes India is using its growing presence in Afghanistan to destabilise Pakistan. India suspects Pakistan of wanting the Afghan Taliban back in power in Kabul to guarantee it a friendly neighbour to the west.
Ironically one area where the two countries' interests may converge is the same one that has divided them most in the past -- the role of Punjabi-based groups such as the Lashkar-e-Taiba.
India accuses Pakistan's ISI spy agency of creating these groups to give Pakistani muscle to Kashmiri separatists. But analysts say they appear to have turned against the military, colluding in attacks against the Pakistan Army and even the ISI.
Spread out in the Punjabi heartland, they are potentially a far more serious threat to Pakistan than the Taliban militants in the Swat valley who have grabbed the world's attention.
And they are also believed to have built links with Al -Qaeda. "That's far more scary," said Nawaz.
But persuading India and Pakistan to make common cause against them could be as hard as ending the Kashmir dispute.
"Yes, we have a common enemy," said Kanwal. "But we'll never be able to coordinate our fight against this common enemy unless the Pakistanis also wake up and realise that we have a common enemy."
"Pakistan really does want to work with India to stop the growth of fundamentalist/terrorist gangs. But India will take a great deal of convincing," said Cloughley.