WASHINGTON -- Iraq's approval of a security pact that sets a three-year timeframe for U.S. troops to leave will put future U.S.-Iraq relations on a strong footing, the White House said Thursday. 

White House press secretary Dana Perino said the Iraqi presidential council's approval of the agreement was a "remarkable achievement" for both nations. It will guide the U.S. relationship with Iraq and help solidify Iraq's progress toward democracy, she said. 

Under the deal, U.S. forces will withdraw from Iraqi cities by June 30, 2009, and from the entire country by Jan. 1, 2012. 

"We have a path now to help our troops get home," Perino said. "And we are already bringing troops home, and we're going to be able to continue to do that as long as we solidify the gains that we've made." 

The agreement, however, includes a caveat that it should go before Iraqi voters in a referendum by the end of July -- when the deal will already be in effect. That was a concession to Sunni demands and means the agreement could be rejected next year if, for example, anti-U.S. anger builds and demands for an immediate withdrawal grow. 

"If there is a national referendum, Iraq is a sovereign country, and they could decide to do lots of different things with it," Perino said. "But I think that the fact that their representative leadership has signed this agreement today that they recognize that they are going to continue to need your help for the next little while."