MANAS TRANSIT CENTER Kyrgyzstan (Reuters) - The United States on Tuesday handed back its only Central Asian airbase to the government of Russia's close ally Kyrgyzstan, as President Barack Obama winds down U.S. involvement in Afghanistan and Moscow makes a comeback in its old imperial backyard. In a move aimed at pleasing its former overlord Russia, parliament in Kyrgyzstan voted a year ago to give Washington until July 11 to vacate the Manas Transit Center, which has served U.S. operations in Afghanistan since 2001. The base, at the main civilian airport in the former Soviet republic, moved more than 5.3...