WASHINGTON (APP) - Pakistan remains a very important counter-terror partner for the United States and Washington is having conversations with Islamabad to work through issues steming from May 2 Abbottabad operation, a top aide to President Obama said. US National Security Advisor Tom Donilon would not comment on controversy surrounding American presence on Pakistani Shamsi Airbase but said the Obama administration would continue its intense and relentless campaign to debilitate and defeat al-Qaeda in South Asia and elsewhere. The Pakistanis and the United States have a complicated relationship. And there are going to be frustrations and disagreements. We remain engaged with Pakistan for a number of very important reasons related to our national security, and I think, ultimately their security, he told CNNs GPS programme aired Sunday. The May 2 American unilateral action on Abbottabad hideout of al-Qaeda chief eliminated Osama bin Laden but caused serious strains in the US-Pakistan bilateral relationship, considered by experts as key to a successful outcome in neighbouring Afghanistan. They (Pakistanis) are a very important counterterrorism partners for the United States. The Pakistanis have lost thousands of military and civilians to the extremists. More extremist groups and individuals have been attacked and taken down in Pakistan than any place outside in the world, the national security advisor said in acknowledgement of the South Asian countrys sacrifices in the anti-terror struggle. The US, Donilon said, has obviously had an important set of conversations with Pakistan , difficult conversations, since the raid on the Osama bin Laden compound in Abbottabad. We are committed to working through these issues as we believe it is in our national interest to do so. In answer to a question, he reiterated that the Pakistani political, military and intelligence leadership had no foreknowledge that bin Laden was hiding in Abbottabad.