WASHINGTON - US President Barack Obama defended the use of drones to target and assassinate Americans overseas suspected of working with terrorists, insisting the government is following the law on what it can and cannot do.

But he admitted the public needs to know more about how the drone programme works and what rules the administration is following. “What I think is absolutely true is that it is not sufficient for citizens to just take my word for it that we are doing the right thing,” Obama said in an online chat sponsored by Google.

Asked if the United States could target a United States citizen on American soil, Obama said, “No.” “There has never been a drone used on an American citizen on American soil, and we respect and have a whole bunch of safeguards in terms of how we conduct counterterrorism in the United States,” he added.

But he said the rules outside the US are “different” — and said it was his responsibility as the president to work with Congress to implement a “mechanism” to be more forthcoming with the public, so that people understand “what is going on, what the constraints are, (and) what the legal parameters are”.

“That is something I take very seriously,” Obama said, “I am not somebody who believes that the president has the authority to do whatever he wants or whatever she wants whenever they want under the guise of terrorism.”

During the hourlong chat, Obama also defended his handling of immigration reform, insisting his ability to change the system has been hampered by bickering in Congress.

“I am the president of the United States. I am not the emperor of the United States,” Obama said. “My job is to execute laws that are passed, and Congress right now has not changed what I consider to be a broken immigration system.”

He said he was waiting to see the specifics of what Congress will come up with immigration reform, insisting he didn’t want to jump into the middle of the debate and complicate already tense.