After months of waiting that ultimately triggered an American Civil Liberties Union lawsuit under Freedom of Information Act, the United States government has for the first time offered a legal justification for its' Predator drone program.

The principle upon which unmanned weapons are deployed, according to a state department legal adviser, is "self defense" under international law.

The CIA attacks by unmanned aircraft in Pakistan, Somalia and elsewhere have sharply increased under President Barack Obama's administration but have remained shrouded in secrecy, with some human rights groups charging the bombing raids amount to illegal assassinations.

Broaching a subject that has been off-limits for official comment, State Department legal advisor Harold Koh laid out the legal argument for the strikes in a speech late Thursday, referring to "targeting" of Al-Qaeda and Taliban figures without mentioning Pakistan or where the raids are carried out.

The United States was in "an armed conflict" with Al-Qaeda, the Taliban and its affiliates as a result of the September 11 attacks, Koh said, "and may use force consistent with its inherent right to self-defense under international law."

"With respect to the subject of targeting, which has been much commented upon in the media and international legal circles, there are obviously limits to what I can say publicly," he told a conference of the American Society of International Law.

"What I can say is that it is the considered view of this administration -- and it has certainly been my experience during my time as legal adviser -- that US targeting practices, including lethal operations conducted with the use of unmanned aerial vehicles, comply with all applicable law, including the laws of war."

The CIA would not comment on the speech.

A Freedom of Information Act request for this information was filed by the ACLU in January, but had for months gone unanswered. Finally, earlier in March, the civil rights watchdog group sued, claiming the public has a right to know the legal grounds upon which the program stands, along with basic data on lethality and civilian casualties.

"We're encouraged that Koh has articulated the legal rationale for the program," said Jonathan Manes, a legal fellow at the ACLU. But he added that he hoped the administration would provide a more detailed account of its legal justification.

"The public has a right to know whether the targeted killings being carried out in its name are consistent with international law and with the country's interests and values," said Jonathan Manes, a legal fellow with the ACLU National Security Project, in a media advisory released after the group's lawsuit was filed. "The Obama administration should disclose basic information about the program, including its legal basis and limits, and the civilian casualty toll thus far."

The group added: "The CIA and the military have used unmanned drones to target and kill individuals not only in Afghanistan and Iraq but also in Pakistan and, in at least one case in 2002, Yemen. The technology allows U.S. personnel to observe targeted individuals in real time and launch missiles intended to kill them from control centers located thousands of miles away. Recent reports, including public statements from the director of national intelligence, indicate that U.S. citizens have been placed on the list of targets who can be hunted and killed with drones."

"While the Obama administration may legitimately withhold intelligence information as well as sensitive information about military strategy, it should disclose basic information about the scope of the drone program, the legal basis for the program and the civilian casualties that have resulted from the program," argued ACLU attorney Jameel Jaffer, who heads the non-profit's National Security Project.

Rights activists and some legal experts charge the drone strikes in Pakistan and other countries, outside of a traditional battlefield, amount to extrajudicial executions that violate both international and US law.

Koh, a fierce critic of former president George W. Bush's policies before he took his post, disagreed -- saying a US ban on government sanctioned assassinations did not apply.

Under US law, "the use of lawful weapons systems -- consistent with the applicable laws of war -- for precision targeting of specific high-level belligerent leaders when acting in self-defense or during an armed conflict is not unlawful, and hence does not constitute 'assassination,'" he said.

He also argued that the US government was not obliged to offer legal rights to the militant figures targeted in the strikes as the United States was at war and acting in self-defense.

Koh said the government was careful to limit attacks to only "legitimate" military objectives and to ensure attacks adhered to the principle of "proportionality," keeping civilian casualties to a minimum.

Civilian deaths from the drone war have triggered popular anger and fed anti-US sentiment in Pakistan.

Pakistan publicly criticizes the targeted assassinations but quietly cooperates with the Americans, analysts say, with Islamabad allowing the use of an air base on Pakistani soil -- a detail a US senator accidentally let slip at a hearing last year.

With AFP.