NEW YORK - Despite threats of retaliation from militants, the United States intends to step up its drone strikes in tribal areas and may extend them deeper inside the country, the New York Times reported Tuesday. On Sunday, a Taliban leader vowed to unleash two suicide attacks a week, similar to Saturdays Islamabad blast, unless the CIA stopped firing missiles in the region. Pakistani officials have already expressed concern that the missile strikes fuel more violence in the country. The NYT report, about the plans to broaden drone attacks, coincided with the presence in Pakistan of Admiral Mike Mullen, the chairman of the Joint Chiefs of Staff, and Richard Holbrooke, the special envoy to the region. The Times quoted US officials as saying that the plan to intensify missile strikes underscored President Obamas goal to disrupt, dismantle and defeat Al-Qaeda in Pakistan and Afghanistan, as well as to strike at other militant groups. Officials are also proposing to broaden the strikes to Baluchistan unless Pakistan reduces the incursion of militants there, the report said. Democrat Senator Carl Levin, who heads the Armed Services Committee, acknowledged last week that the price is very heavy when missile strikes mistakenly kill civilians, but he said the strikes were an extremely effective tool. The paper also quoted military experts as saying that the drones which can transmit live video for nearly a day at a time, typically supply the weapons targeting officers with enough information to avoid civilian casualties. Marc Garlasco, a former military official, has said the drones had helped limit civilian casualties in Afghanistan and Iraq, where the Air Force uses them to attack people laying roadside bombs. In Pakistan, the missile strikes have been limited to the tribal areas, and authorities say they have killed 9 of the top 20 Qaeda leaders. US officials say the missile strikes have forced some Taliban and Qaeda leaders to flee towards Quetta. The final preparations for strikes in Pakistan take place in a crowded room lined with video screens, where CIA officers work at phone banks and National Security Agency personnel monitor electronic chatter, the paper said. The intelligence officers watch scratchy video captured by the drones, which always fly in pairs above the targets. Generally the head of the CIAs clandestine service or his deputy gives the final approval for a strike. The decision about what type of weapon to use depends on the target, a former intelligence official said. Top security leaders approve lists of people who can be attacked and the lawyers determine whether each attack can be justified under international law, officials added.