FACTBOX-Key Quotes from US Republican Presidential Debate

(Reuters) - Republican candidates vying for the chance to take on U.S. President Barack Obama in 2012 faced off in South Carolina in a debate Saturday.

Here are some of their main quotes.

MITT ROMNEY, FORMER MASSACHUSETTS GOVERNOR

On Iranian nuclear ambitions:

"If we re-elect Obama, Iran will have a nuclear weapon. If we elect Mitt Romney, if we elect me as the next president, they will not have a nuclear weapon."

On U.S. trade with China:

"We can't just sit back and let China run all over us. People say, well, you'll start a trade war. There's one going on right now, folks. They're stealing our jobs and we're going to stand up to China."

On U.S. exceptionalism:

"We have a president right now who thinks America is just another nation. America is an exceptional nation. ... I believe the way to conduct foreign policy is with American strength."

HERMAN CAIN, FORMER PIZZA EXECUTIVE

On U.S. military action against Iran:

"Not at this time. I would not entertain military opposition."

How he would receive advice from military advisers:

"Because I'll have a multiple group of people offering different recommendations, this gives me the best opportunity to select the one that makes the most amount of sense. But ultimately it's up to the commander-in-chief to make that decision.

Defending the practice of waterboarding, a type of simulated drowning:

"I agree that it was enhanced interrogation technique. ... Yes, I would return to that policy. I don't see it as torture. I see it as enhanced interrogation technique."

RICK PERRY, TEXAS GOVERNOR

Declaring a "starting at zero" foreign aid policy:

"The foreign aid budget in my administration for every country is going to start at zero dollars. Zero dollars. ... Then we'll have a conversation in this country about whether or not a penny of our taxpayer dollars needs to go into those countries."

Interrupting the moderator's question about Perry's proposal to eliminate the Department of Energy:

"I'm glad you remembered it."

Responding to a question on U.S. cybersecurity and China:

"I happen to think that the communist Chinese government will end up on the ash heap of history if they do not change their virtues."

NEWT GINGRICH, FORMER SPEAKER OF THE HOUSE OF REPRESENTATIVES

On Perry's foreign aid policy:

"You ought to start off with zero and say, 'Explain to me why I should give you a penny.' ... The Pakistanis hid bin Laden for at least six years in a military city within a mile of their national defense university. And then they got mad at the people who turned him over to us."

On aid and policy towards post-revolutionary Egypt:

"It would certainly be completely rethought. ... The degree to which the Arab spring may become an anti-Christian spring is something which bothers me a great deal. I would certainly have the State Department intervening on behalf of the Christians who are being persecuted under the new system having their churches burned, having people killed.

MICHELE BACHMANN, U.S. CONGRESSWOMAN FROM MINNESOTA

On the use of waterboarding:

"If I were president, I would be willing to use waterboarding. I think it was very effective. It gained information for our country."

Criticizing Obama's treatment of Israel:

"It seems that the table is being set for worldwide nuclear war against Israel. And if there's anything that we know, President Obama has been more than willing to stand with Occupy Wall Street, but he hasn't been willing to stand with Israel."

RON PAUL, U.S. CONGRESSMAN FROM TEXAS

On the use of torture:

"Why would you accept the position of torturing a hundred people because you know one person might have information? And that's what you do when you accept the principle of torture. I think it's -- I think it's uncivilized and -- and have no practical advantages and it's really un-American to accept, on principle, that we will torture people that we capture."

RICK SANTORUM, FORMER U.S. SENATOR FROM PENNSYLVANIA

On the threat of a nuclear Iran:

"We should be working with Israel right now to do what they did in Syria, what they did in Iraq, which is take out that nuclear capability before the next explosion we hear in Iran is a nuclear one and then the world changes."

JON HUNTSMAN, FORMER U.S. AMBASSADOR TO CHINA

Why U.S. troops should come home from Afghanistan:

"I say this nation's future is not Afghanistan. This nation's future is not Iraq. This nation's future is how prepared we are to meet the 21st century challenges, that's economic and that's education."

(Compiled by Lily Kuo; Editing by Will Dunham)