U.S. Bombs Iranian Guerrilla Forces Based in Iraq By DOUGLAS JEHL ASHINGTON, April 16 — American forces have bombed the bases of the main armed Iranian opposition group in Iraq, a guerrilla organization that maintained thousands of fighters with tanks and artillery along Iraq's border with Iran for more than a decade. The group, the Mujahedeen Khalq, has been labeled a terrorist organization by the United States since 1997, and Bush administration officials said the group had supported Saddam Hussein's military. Still, the biggest beneficiary of the strikes will be the Iranian government, which has lost scores of soldiers in...