WASHINGTON, April 11 (UPI) -- U.S. Army Gen. David Petraeus and his boss, Defense Secretary Robert Gates, differ about when troop withdrawals from Iraq could resume.

Gates, testifying before a Senate committee Thursday, said he hoped troop reductions in Iraq could resume after a "brief," 45-day pause this summer, the Los Angeles Times reported Friday.

However, Petraeus, during two days of testimony, said drawdowns would resume only when conditions permit and did not offer a timetable. President George Bush said Petraeus would have "all the time he needs" to assess troop levels.

"My view is that (Petraeus) should be in a position at the end of that 45-day period of evaluation and consolidation to make a determination whether a next further drawdown could take place," Gates said. "One of the benefits of being secretary of defense ... is that I'm more allowed to hope than the field commander is."

Testifying with Gates, Joint Chiefs of Staff Chairman Michael Mullen said U.S. troops could train Iraqi forces and move the Iraqi government toward political reconciliation while the number is reduced.

"I see no reason why we cannot accomplish these goals while also keeping open the option of an informed drawdown of forces throughout the remainder of this year," Mullen said.