SEOUL, South Korea -- A U.S. aircraft carrier deployed off South Korea's coast Friday to take part in a major joint military exercise despite objections by North Korea.
The Japanese government, meanwhile, said it was considering strengthening its missile defenses amid reports that North Korea is preparing to test a medium-range missile capable of reaching Japan.
"The government is investigating and considering both legal and budgetary issues regarding missile defense," Defense Agency spokesman Ichiro Imaizumi said in Tokyo. He declined to be more specific.
The announcement came a day after Japan's Defense Agency said it had deployed an Aegis-equipped destroyer -- which includes top-of-the-line surveillance systems and ship-to-air missiles -- in the waters between Japan and North Korea.
A major newspaper, the Yomiuri Shimbun, reported Friday that Tokyo plans to acquire advanced U.S.-made Patriot antimissile rockets to deploy.
If North Korea fired one of its mid-range Rodong missiles at Japan, the plan would call for Tokyo to intercept it with an enhanced version of the Patriot PAC2 capable of intercepting ballistic missiles that have a range of 620 miles, according to the report.
Japan currently has less-advanced Patriot antimissile rockets at 27 locations, but they have a shorter range.
The United States also has raised its military profile in the region, with the aircraft carrier USS Carl Vinson arriving off South Korean and the Air Force resuming reconnaissance flights, suspended since North Korean jets briefly intercepted a U.S. spy plane March 2.
On Friday, the U.S. military showed off one of the six F-117 Nighthawk stealth fighters it has brought to South Korea for the major U.S.-South Korean military exercise this month. Officials insisted the fighters were strictly for training and would leave the region when the annual exercise, dubbed Foal Eagle, wraps up April 2.
"One of the valuable parts of these exercises is we get experience flying in South Korean airspace," Lt. Col. Jay Lake said at Kunsan Air Base south of Seoul. "Our mission is going against big, valuable, heavily defended targets."
North Korea objects to the U.S. military maneuvers, calling them a rehearsal for invasion.