WASHINGTON (Reuters) - The futuristic F-22A "Raptor" fighter jet, designed to dominate the skies well into the 21st century, joined the U.S. combat fleet on Thursday, 20 years after it was conceived to fight Soviet MiGs over Europe. The Air Force said "initial operational capability" had been achieved by 16 of the aircraft at the 1st Fighter Wing's 27th Fighter Squadron at Langley Air Force Base, Virginia. Pilots in the squadron, the Air Force's oldest in continuous operation, have been training on the F-22 for about a year. "When asked to go to war, they're ready," said the 1st Fighter...