US President Barack Obama lauded George W. Bush Thursday as a leader of "incredible strength and resolve" who faced a storm of terrorism head on, at the opening of his predecessor's library.

In a rare gathering of all living US presidents, partisan divides were hinted at but put aside, as Bush was painted as a man of courage and compassion, in front of a building meant to shore up his place in history.

"He is comfortable in his own skin. He knows who he is ... he is a good man," Obama said of Bush, who blinked quickly, and set his jaw as he fought back emotion, as he won praise from the exclusive club of presidents.

Obama praised Bush for the "incredible strength and resolve" Bush projected through a bullhorn when he stood on a pile of rubble at Ground Zero in New York after the September 11 attacks.

Despite his sharp previous claims that Bush stained the US image abroad with the pre-emptive war in Iraq and his anti-terror policies and crashed the American economy, Obama thanked Bush for his advice when he took office.

"No one can be completely ready for this office. America needs leaders who are ready to face the storm head on .... that is what president George W. Bush chose to do," Obama said.

The new 226,000 square foot building on the campus of Southern Methodist University in Dallas includes an archive of Bush's presidential papers, a museum stuffed with artifacts of his two terms and a policy institute.

Bush's facility is dominated by memories of the September 11 attacks, which gave life to Bush's global war on terror, and includes a steel beam twisted in the inferno of the World Trade Center.

In one of the most poignant moments of the ceremony, 88-year-old George H.W. Bush made a few off the cuff remarks from his wheelchair, to which he is now largely confined following a bout with illness this year.

Both former Democratic presidents Bill Clinton and Jimmy Carter meanwhile praised Bush for his program to fight AIDS and HIV in Africa which is credited with saving millions of lives.

"I like president Bush," Clinton said.

Former world leaders who were closest to Bush during his terror-seared first term, the march to war with Iraq and the months of recrimination afterwards were also in Dallas to honor their former comrade-in-arms.

Former British prime minister Tony Blair and his wife Cherie, former Australian prime minister John Howard, who was in Washington on September 11, 2001, and ex-Italian prime minister Silvio Berlusconi were on the guest list.

Other guests of honor included Israel's Ehud Olmert, Spain's Jose Maria Aznar and former South Korean president Lee Myung-Bak.

In a series of interviews to pave the way for the opening of the library, financed by private benefactors, Bush made clear that he is not prone to second guessing in his retirement, in which he has kept out of the public eye.

Asked by ABC News whether he had any second thoughts about the 2003 invasion of Iraq, which is convulsed in a new wave of violence, Bush said: "I am comfortable in the decision-making process."

"I think the removal of Saddam Hussein was the right decision for not only our own security but for giving people a chance to live in a free society," Bush said.

"But history will ultimately decide that, and I won't be around to see it.

"As far as I'm concerned, the debate is over. I mean, I did what I did."

The US invasion swiftly toppled Saddam Hussein but the mismanaged aftermath of the war led to US forces becoming embroiled in a prolonged insurgency.

And the weapons of mass destruction which were the spur for the war were never found.

The library's story is of a president who thought he was going be occupied with domestic policy only to find himself defending the homeland from Al-Qaeda.

Bush left office in 2009 as one of the most unpopular presidents in recent history, with a Gallup approval rating of just 34 percent.

His absence from the scene seems to have improved his image slightly: in a CNN/ORC poll Wednesday, 42 percent said Bush's presidency was a success.

The centerpiece of the Bush library is an interactive exhibit known as "Decision Points Theater" which asks visitors to decide what they would have done on issues like Iraq, Hurricane Katrina in 2005 and the financial crisis.

The ex-president then pops up on a screen to justify the steps he actually did take.