U.S. Defense Secretary Robert Gates declared Afghanistan the top U.S. military priority on Tuesday but said U.S. objectives there should be “limited” as the Pentagon nearly doubles the number of U.S. troops in the country by mid-summer. “My own personal view is that our primary goal is to prevent Afghanistan from being used as a base for terrorists and extremists to attack the United States and our allies,” Gates told the Senate Armed Services Committee. “Whatever else we need to do flows from that objective.” Amid preparations for a major troop increase in Afghanistan, Gates warned that the United States must not maintain the unrealistic goal of turning the country into a rich nation. “If we set ourselves the objective of creating some sort of Central Asian [heaven] over there, we will lose, because nobody in the world has that kind of time, patience, or money,” he said. Gates' testimony marked a significant narrowing of U.S. ambitions even as the Obama administration prepares to nearly double the size of its forces in Afghanistan. Gates told lawmakers that the Pentagon could send two more brigades to Afghanistan by late spring and a third by mid-summer in an effort to reverse the security situation in a country troubled by corruption and increasing violence. While the majority of the 30,000-soldier increase requested by the U.S. commander in Afghanistan, General David McKiernan, would be in place by mid-summer, Gates said bases must be expanded to receive the full number of additional troops. “I would be very skeptical of additional forces levels, American force levels, beyond what General McKiernan has already asked for,” Gates told lawmakers. Regarding Iraq, Gates said the Pentagon was drafting a range of options for withdrawing the 142,000 U.S. troops there, including the withdrawal of all 14 combat brigades from Iraq in 16 months.