Amid a contentious debate on how to deal with terror suspects held at the Guantanamo prison, US President Barack Obama on Thursday vowed to break from Bush-era policies and tried to convince Americans he can make it right.

US President Barack Obama delivers a major speech on national security at the US National Archives in Washington, DC.[Xinhua]

"In all of the areas that I have discussed today, the policies that I have proposed represent a new direction from the last eight years," he said in a nationally-televised speech on national security.

"We will vigorously protect our people while forging a strong and durable framework that allows us to fight terrorism while abiding by the rule of law," Obama noted.

Guantanamo a "moral setback"

Defending his plan to close the detention facility at US naval base in Guantanamo Bay, Cuba within one year, the president said explicitly that "there is no question that Guantanamo prison set back the moral authority that is America's strongest currency in the world."

"Instead of building a durable framework for the struggle against al-Qaida that drew upon our deeply held values and traditions, our government was defending positions that undermined the rule of law," said Obama.

"Indeed, part of the rationale for establishing Guantanamo in the first place was the misplaced notion that a prison there would be beyond the law -- a proposition that the Supreme Court soundly rejected," he said.

"Meanwhile, instead of serving as a tool to counter-terrorism, Guantanamo became a symbol that helped al-Qaida recruit terrorists to its cause," said Obama.

"So the record is clear: rather than keep us safer, the prison at Guantanamo has weakened American national security," noted the president.

"By any measure, the costs of keeping it open far exceed the complications involved in closing it. That is why I argued that it should be closed throughout my campaign. And that is why I ordered it closed within one year," he stressed.

The president acknowledged that closing the prison will be "difficult and complex".

"The problem of what to do with Guantanamo detainees was not caused by my decision to close the facility; the problem exists because of the decision to open Guantanamo in the first place," he noted.

Obama said there are no neat or easy answers, but "the wrong answer is to pretend like this problem will go away if we maintain an unsustainable status quo."

The president also said he could not "disagree more" with proponents of so-called "enhanced interrogation techniques" such as water boarding.

"As Commander-in-Chief, I see the intelligence, I bear responsibility for keeping this country safe, and I categorically reject the assertion that these are the most effective means of interrogation," Obama noted.