WASHINGTON (Agencies) - The US will keep targeting Al-Qaeda anywhere in the world, including in countries unable or unwilling to do it themselves, the top US counterterror official said Friday. White House counterterror chief John Brennan laid out what could be called the Osama bin Laden raid doctrine, in remarks at Harvard Law School. He said under international law, the US can protect itself with pre-emptive action against suspects the US believes present an imminent threat, wherever they are. That amounts to a legal defence of the unilateral Navy SEAL raid into Pakistan that killed Al-Qaeda mastermind bin Laden in May, angering Pakistan. It also explains the thinking behind other covert counterterrorist action, like the CIAs armed drone campaign that only this week killed a top Al-Qaeda operative in Pakistans tribal areas. The Obama administration has quadrupled drone strikes against Al-Qaeda targets since taking office. The Obama administration has more recently expanded drone strikes and the occasional special-operations raid into areas like Somalia, where the government may be willing to fight Al-Qaeda, but lacks the resources. Navy SEALs targeted Al-Qaeda operative Saleh Ali Saleh Nabhan in Somalia in 2009, by helicopter. The SEALs then landed to pick up his body and bury it at sea, just as bin Laden was later interred. We reserve the right to take unilateral action if or when other governments are unwilling or unable to take the necessary actions themselves, Brennan said. Yet Brennan followed that by saying that does not mean the US can use military force 'whenever we want, wherever we want. International legal principles, including respect for a states sovereignty and the laws of war, impose important constraints on our ability to act unilaterally. Brennan did not explain how that constraint applied, when the US Navy SEALs entered Pakistani territory to go after Bin Laden, without Pakistani government knowledge or permission. He said the US prefers to work with countries where the targets hide, as it does in Yemen. The US has expanded counterterrorist cooperation with the Yemeni government, which allows the US to fly armed drones, and other types of surveillance, pairing US special operations forces with its own troops, and even conducting the occasional air strike, fired from a ship offshore, or dropped from a jet. The senior counterterrorist official said the US prefers to capture rather than kill terror suspects whenever possible, an apparent answer to critics who allege the administration has authorised the killing of terrorists as it has no place to hold them, with the status of the Guantanamo detention facility still in limbo. It is the unqualified preference of the administration to take custody of that individual so we can obtain information, he said. Brennan reiterated the admins commitment to prosecuting terror suspects in federal courts, but reserved the right to try them by military commissions - a position that offends both the Obama administrations left wing base, which wanted military commissions ended, and many top Republican officials who dont want to grant terror suspects the same rights as US citizens, by trying them inside the US. John Brennan, President Barack Obamas top advisor for counterterrorism and homeland security, also criticized Friday attempts by some lawmakers to ensure that military, rather than civilian courts deal with terror suspects. Brennans speech at Harvard Law School later Friday laid out the legal questions surrounding US counterterrorism operations, especially the widening geographical spread of US military strikes against extremists. The United States does not view our authority to use military force against Al-Qaeda as being restricted solely to 'hot battlefields like Afghanistan, Brennan said. We reserve the right to take unilateral action if or when other governments are unwilling or unable to take the necessary actions themselves. However, Brennan added, that does not mean we can use military force whenever we want, wherever we want. International legal principles, including respect for a states sovereignty and the laws of war, impose important constraints on our ability to act unilaterally-and on the way in which we can use force-in foreign territories. The New York Times earlier quoted administration and congressional officials as saying that the Obama team was divided on the legal leeway the United States had in killing Islamist militants in Yemen and Somalia. The paper said the discussion, pivotal to the future course of the anti-terror fight, centered on the extent to which Washington could escalate drone strikes, cruise missiles or commando raids from current high value Al-Qaeda targets to target thousands of extremist foot soldiers. Meanwhile, The Washington Post reported late Friday that the Obama administration had significantly increased the frequency of drone strikes and other air attacks against Al-Qaeda in Yemen. Some of the the strikes, carried out by the militarys Joint Special Operations Command, have been focused in the southern part of the country, where insurgent forces have for the first time conquered and held territory, the paper said. Unlike in Pakistan, where the CIA has presidential authorization to launch drone strikes at will, each US attack in Yemen and nearby Somalia requires White House approval, The Post said. In his speech, Brennan also took issue with administration critics on Capitol Hill who are seeking to mandate that all terror suspects are treated as enemy combatants and held in military custody rather than in the civilian court system. I am deeply concerned that the alternative approach to counterterrorism being advocated in some quarters would represent a drastic departure from our values and the body of laws and principles that have always made this country a force for positive change in the world, Brennan said. Such a departure would not only risk rejection by our courts and the American public, it would undermine the international cooperation that has been critical to the national security gains we have made. Our counterterrorism professionals regardless of the administration in power need the flexibility to make well-informed decisions about where to prosecute terrorist suspects.