Thomson ReutersMOSCOW - The Russian Defence Ministry said on Saturday it had sent a fighter plane on Friday to intercept a U.S. aircraft approaching its border over the Baltic Sea because the American plane had turned off its transponder, which is needed for identification. The Pentagon said the U.S. Air Force RC-135 plane had been flying a routine route in international airspace and that the Russian SU-27 fighter had intercepted it in an "unsafe and unprofessional" way. CNN reported that the Russian jet had come within about 100 feet (30 meters) of the U.S.