ISLAMABAD - The United States is considering various options including typical hardcore solutions based on its carrot and stick policy in repairing strained relations with Pakistan by demanding military operation in North Waziristan Agency without any further delay. Well-placed diplomatic sources told The Nation on Sunday that Washington had been weighing various options in response to Islamabads March 17 strong protest with the United States over its inhuman drone hit on a peace congregation in North Waziristan Agency. The US drone attack on a peace congregation, which killed at least 39 innocent people, had drawn a strong and rare condemnation both from civilian and military leadership of Pakistan which led to serious friction in relations between the two countries. The sources said that there had been zero communication between the State Department and Minister of Foreign Affairs of Pakistan since March 17 when the Foreign Office summoned US Ambassador to Pakistan Cameron Munter and lodged a strong protest over the drone strike. Ambassador Munter on this occasion pledged to leave for Washington on March 19 to hand over Pakistans press note but failed, and instead revisited the Foreign Office on March 25 to invite Foreign Secretary Salman Bashir for a visit to the United States. Pakistan had boycotted to participate in a trilateral meeting of Afghanistan, Pakistan and United States in Brussels on March 26 as a mark of protest ostensibly with the view that Washington would tender an apology but so far it has not happened since 17 March. However, in the meantime the United Sates instead of any response kept Islamabad isolated instead and has been weighing various options with major focus on pressuring Pakistan to launch a meaningful military operation in North Waziristan, a region blamed as hub of terrorists. That day is not far away when Washington using threatening tones would call for a ruthless military operation against the alleged terrorist hideouts in the North Waziristan. The US policymakers have already approved this as one of the options in case Pakistan doesnt budge from its stand, the sources said. Pakistan has been resisting US pressure seeking a meaningful military operation in North Waziristan with this plea that its military leadership would decide about it when deemed necessary. From the very outset, Pakistan has been in opposition to the US drone attacks arguing that such actions were counterproductive. The sources further said that US wanted to have relations with Pakistan on its own terms that had been a serious source of contention between the two countries to further increase their bilateral cooperation. APP adds: US Special Representative for Afghanistan and Pakistan Ambassador Marc Grossman has expressed regrets for civilian casualties in Pakistan, paving the way for resolving disagreement between the two allies after a drone strike in North Waziristan on March 17 killed several tribal elders. Grossman was speaking during a panel at the Brussels Forum entitled, 'Bridging the Trust Deficit with Pakistan, along with UK Defence Secretary Liam Fox and journalist Ahmed Rashid. Grossman insisted that the object of the US mission in Afghanistan and its cooperation with Pakistan was protecting people and improving their lives, and when civilians are killed, we regret it. We deeply regret it. Grossman was asked about the civilian casualties from done strikes by Steve Erlanger of the New York Times. He stressed that he could not go into specific operations, reflecting US policy of avoiding public discussion of drone strikes. I cant discuss all the aspects of every bit of this cooperation, he said about US-Pakistan partnership along the Pakistan-Afghanistan border. If the object is for protecting people and improving their lives, that is a worthwhile endeavour, he added. You know when civilians are killed, we regret it. We deeply regret it, Grossman stated. Earlier, in his introductory remarks, Grossman said, Im not going to answer about this military problem, this military approach or that military approach. Im not even going to answer about all of the cooperation that we have with the Pakistanis. But he said the purpose of the relationship is to make Pakistanis more secure, and Americans and Europeans more secure, and to make Pakistanis more prosperous, thats something were after. He said, We deeply regret civilian casualties when they happen, anywhere, and certainly, and certainly its an important thing to say out loud, to regret those casualties. In expressing regret over civilian casualties, Grossman appeared to be meeting a key Pakistani condition in the aftermath of the North Waziristan drone strikes that resulted in the death of 41 people including tribal elders and drew condemnation from Pakistans civilian as well as military leaders, including Army Chief General Ashfaq Parvez Kayani. Pakistans Foreign Secretary Salman Bashir had conveyed to the US ambassador in Islamabad Pakistans decision that Islamabad was not attending a trilateral meeting with the US and Afghanistan in Brussels scheduled for March 26 and Pakistans ambassador to the US Husain Haqqani had demanded that the US should apologise for civilian deaths from its military and intelligence operations.