Last updated on: September 30, 2016 12:33 IST

Immediately after India launched its surgical strikes, sources said, it had informed the US of its action.

Aziz Haniffa reports from Washington, DC.

Senior US intelligence and Congressional sources privy to intelligence reports and classified briefings have told Rediff.com of "the growing body of irrefutable evidence of Pakistani complicity" in the Uri terrorist attack that the US had "gathered independently" which it found to be in sync with the "proof of evidence India has shared" with Washington, as part of the unprecedented counter-terrorism cooperation between the two countries in recent years.

The sources acknowledged that it was this evidence that had led to US Secretary of State John F Kerry, National Security Adviser Susan Rice, US Senators Mark Warner and John Cornyn and other senior administration officials to call on Pakistan to act against State Department and United Nations designated terrorist groups operating from Pakistan, often inspired and supported by the ISI, Pakistan's intelligence services.

The interactions, phone calls and messages by these officials and US Senators with Pakistani Prime Minister Nawaz Sharif, India's External Affairs Minister Sushma Swaraj, National Security Adviser Ajit Doval and Prime Minister Narendra Modi respectively, the sources noted, was in anticipation of "the inevitability" of the Indian surgical strikes across the Line of Control against terrorists launching pads and "the less than lukewarm reaction" by the US when it happened, was in some sense subtly condoning India's actions, although publicly calling for restraint.

There was now concern over the escalating tensions and the possibility of a conflict that had resulted in a flurry of activities by US officials with their counterparts in both Delhi and Islamabad, manifest by US Ambassador to India Richard Rahul Verma -- in Washington to address the Woodrow Wilson Centre on Thursday, September 29 -- canceling his appearance and taking the next plane back to Delhi to monitor the situation and to impress upon India to keep the lines of communication open with Pakistan and not up the ante on its recent actions.

The US envoy in Islamabad has also been instructed to do the same and strongly warn Pakistan against contemplating any retaliatory tit-for-tat.

At the White House, spokesman Josh Earnest urging a de-escalation of the tensions between India and Pakistan, lauded the continuing communications between the two militaries and called for these lines to be kept open, even as he said it was imperative that Pakistan come down hard on the terrorist groups in its territory engaged in international terrorism.

A day earlier, on September 28, Rice spoke to Doval by phone and according to the White House 'strongly condemned the September 18 cross-border attack on the Indian Army brigade headquarters in Uri and offered condolences to the victims and their families.' National Security Council spokesman Ned Price said, Rice had 'affirmed President Obama's commitment to redouble our efforts to bring to justice the perpetrators of terrorism throughout the world.'

'Highlighting the danger that cross-border terrorism poses to the region, Price said Rice had 'reiterated our expectation that Pakistan take effective action to combat and de-legitimize United Nations-designated terrorist individuals and entities, including Lakshar-e-Tayiba, Jaish-e-Muhammed, and their affiliates.'

'In the context of the robust US-India partnership, Ambassador Rice discussed our shared commitment with India to pursuing peace and regional stability and pledged to deepen collaboration on counter-terrorism matters including on UN terrorist designations,' Price added.

At the State Department, spokesman Joe Kirby, asked about India's surgical strikes, said, echoing Earnest's statement about Indian and Pakistani militaries being in communication, said, 'We believe that continued communication is obviously importance to reduce tensions.'

He was circumspect when asked if there was any prior consultation between the US and India before the surgical strikes since Kerry had spoken to Swaraj and Rice to Doval, saying only that the secretary of state in his conversation with Swaraj had '‘reiterated his strong condemnation of the September 18 Uri attack,' and also 'condemned terrorism in all its forms and he cautioned against any escalation in tensions.'

When pressed that since this was a counter-terrorism operation and there is strong coordination between India and the US on counter-terrorism issues, if there was coordination on this strike by the Indian forces, Kirby, who was formerly the Pentagon spokesman, said, 'I don't have anything for you on that.'

Immediately after India launched its surgical strikes, sources said, it had informed the US of its action.

Asked about Ambassador Verma's rushing back to Delhi, Kirby said, 'My understanding is that he believed that it was appropriate for him to go back. He's got a big job, there's a lot of responsibilities that come with it, and obviously it's a very dynamic situation, and he felt it was prudent to go back.'

Earlier, during his meeting with Sharif at the UN, as Sharif was raising the Kashmir issue with Kerry, the secretary of state, according to the State Department, 'reiterated the need for Pakistan to prevent all terrorists from using Pakistani territory as safe havens.'

Senators Warner and Cornyn, who co-chair the Senate India Caucus, shrugging aside the diplomatic nuances, said they were troubled over initial indications that the Uri terror attack emanated from Pakistan.

In a letter to Modi said, they said, 'We are greatly concerned about initial indications that the perpetrators of this attack were Pakistani and that the attack emanated from Pakistan. If true, this attack would be just the latest in a series of deadly attacks in India conducted by Pakistan-based terrorist groups.'

'We call on the government of Pakistan to cooperate fully and transparently in this investigation and prosecute any individuals within its territory that participated in this horrendous attack,' Warner and Cornyn said, adding, 'Pakistan's possible involvement in this attack underscores our broader concern about Pakistan's use of terrorism as a pillar of its foreign policies toward Afghanistan and India.'

'As many credible experts have noted, such groups as the Haqqani network, the Tehreek-i-Taliban Pakistan, Lashkar-e-Tayiba, and Jaish-e-Muhammed still operate freely in Pakistan, launching attacks not only on India but also on US personnel and interests in Afghanistan,' the senators added.

'That such terrorist groups continue to operate within Pakistan is unacceptable, and we will work within Congress to pressure Pakistan to end any association with these terrorist groups targeting India, put a stop to their cross-border incursions, and take active and immediate steps to reign in homegrown terrorists,' they pledged.

Warner and Cornyn told Modi that 'the continued threat of terrorism that both India and the US face highlights the critical need to ensure that we continue to expand US-India bilateral defence, intelligence and counter-terrorism cooperation.'

While welcoming the declaration of India as a major defence partner, the senators said, 'Similarly, we are pleased by the finalisation of an arrangement to facilitate the sharing of terrorist screening information and the progress made by the US-India Counter-terrorism Joint Working Group and the Homeland Security Dialogue.'

Meanwhile, buoyed by a bill introduced by Congressman Ted Poe, Texas Republican, to designate Pakistan as a State sponsor of terrorism in the wake of the Uri attack, an online 'We the People' petition launched by a group of Indian Americans on the White House Web site to do just that by September 28 had garnered 265,000 signatories, propelling it as most popular active petition on the White House site.

This would make it incumbent -- as per the guidelines of the 'We the People' petition -- that the Obama administration respond within 60 days if the petition is signed by a minimum of 100,000 people.

The US-India Political Action Committee on September 23 also launched a nationwide effort to canvass Indian Americans to get their local legislators to support H R 6069, the bill introduced by Poe.

'It is time we stop paying Pakistan for its betrayal and designate it for what it is, a State sponsor of terrorism,' Poe had said after introducing the bill.