Philippine President Corazon Aquino said the United States would have three years to withdraw its military forces from the Philippines under a compromise reached yesterday with opponents of the US bases.The agreement caps more than two weeks of confrontation and maneuvering between the Aquino government and the Philippine Senate, which rejected a new 10-year lease for Subic Bay Naval Station, one of the largest US military facilities in the world. Through this compromise, Mrs. Aquino gains breathing room for her cash-strapped country with a more gradual phaseout of thousands of Filipino jobs at the bases. Clark Air Base was heavily damaged by the eruption of Mt. Pinatubo last summer and is slated to be abandoned next year. Aquino said the US would not be expected to pay compensation during the three-year period, although US assistance for Pinatubo victims would be welcome. After the Senate rejection of the 10-year treaty, bases supporters pushed for a seven-year pullout, while opponents insisted the US should withdraw within one year. US officials had announced they were ready to pull out over a four-year period. Smarting from the Senate defiance, Aquino sought to overturn the vote with a referendum on the US presence, hoping to invoke majority support for keeping the US facilities. But the leader, who has said she will not run for reelection next year, was forced to abandon the plan by opposition among her Cabinet ministers and the likelihood of a constitutional battle over the referendum's legality. The US ambassador in Manila, Frank Wisner, said the US would accept the new arrangement and sign an agreement confirming the deal, although no date was specified.