Turning the screws on Pakistan, the United States has said it expects a serious response from its close ally about its spy agency the Inter Services Intelligence (ISI)'s ties with terrorist groups amid growing tensions between Washington and Islamabad that is now being candidly acknowledged by American officials, reports say.

Responding to a query on how closely the ISI is intertwined with terror groups, Bruce Riedel, President Obama's principal adviser on South Asia, said: These are serious issues. We are raising them with the Pakistanis. The head of the ISI (Lieutenant-General Shuja Pasha) was here in February. We have put these issues on the table and we expect to see a serious response. In our engagement with Pakistan, I think our watchword must be an old one: trust but verify.

Riedel's exposition closely follows the riot act read out to Islamabad in this regard by the civilian-military team of American Special Envoy Richard Holbrooke and Joint Chiefs of Staff Admiral Mike Mullen earlier this week.

Asked what the ISI expects to gain from their influence on these groups, Riedel explained that over the course of the last three decades, the ISI used these relations to have leverage against India and influence in Afghanistan.

Riedel became the latest U.S. official to speak bluntly about Islamabad's ties with terrorism despite that country's denials and histrionics during the Holbrooke-Mullen visit when confronted about the ISI's terrorist ties.

The Obama advisor's comments on the Pakistan-terrorism nexus came amid unrelenting pressure from Washington on the Islamic nation to forgo its pursuit of strategic depth and use of terrorism as a state policy.

The Pakistani establishment flew into a rage during the visit to Islamabad earlier this week by the two U.S. policy makers, after its complaints about India did not find any suitable response.

Islamabad's main grouse--and excuse for keeping its terrorism option open--was India's growing influence in Afghanistan which Pakistan found threatening, and lack of progress on resolving the Kashmir issue, which it attributes to New Delhi's intransigence.

Additionally, Pakistani leaders also complained about the drone attacks and the conditions and benchmarks attached to U.S. aid. They wanted for themselves the equipment used in the drone attacks to take on the extremists and no strings attached foreign assistance, saying it should be left to decide how it will spend the billions Washington is lining, ostensibly to save the country from collapse.

For comments and feedback: contact editorial@rttnews.com