U.S. jet fighters intercepted Soviet bombers off northwest Alaska, but the Soviet planes continued east toward Canada instead of heading back to Siberia, the Air Force reported. Usually, Soviet planes on training missions near Alaska leave after Air Force jet interceptors arrive. That did not occur in encounters over the Arctic Ocean last Thursday and Friday, Air Force Capt. Robert Morris of the Alaska Air Command said. In each instance, two four-engine Bear H bombers kept flying east, undeterred by the American F-15 jet fighter interceptors, which shadowed them for hundreds of miles in international airspace.