(Adds estimated cost, defence minister's comment, paragraphs 1-2, 4-5,)
TOKYO, July 30 (Reuters) - Japan said on Monday it had picked Lockheed Martin Corp to build a powerful new $1.2 billion radar for two ground-based Aegis ballistic missile defence stations meant to guard against North Korean missile strikes.
"By using this new radar we will increase our ability to cope with missiles on lofted trajectories raising the level of ballistic missile defence," Japanese Minister of Defence Itsunori Onodera told reporters.
The decision is the latest sign that Japan is forging ahead with plans to reinforce its defences despite a North Korean pledge to denuclearise. The purchase could also help Tokyo ease trade friction with Washington as its key ally threatens to impose tariffs on Japanese auto imports.
The two radars will cost around 130 billion yen ($1.17 billion) each, with maintenance and other operational costs putting the estimated budget at the two sites over 30 years at 466 billion yen, according to a Ministry of Defence news release.
Other outlays, including for missile launchers, interceptors, buildings and defences for the two sites, will add to the final tally.
The radar decision means Aegis Ashore can be added to a defence budget proposal slated for release next month ahead of any meeting between Japanese Prime Minister Shinzo Abe and U.S. President Donald Trump in September, when Abe is expected to attend the United Nations in New York.
Trump has cranked up pressure on Tokyo with tariffs on steel and threats of levies on car imports, although during a visit to Tokyo in November he welcomed Japan's procurement of Lockheed Martin F-35 stealth fighters and urged Japan to buy more U.S. weapons and "billions and billions of dollars of additional products of all kinds".
The Aegis Ashore radar choice was between Raytheon Co's Spy-6 radar, designed to upgrade the U.S. Navy's fleet of Aegis warships, and a version of Lockheed Martin Corp's Long Range Discrimination Radar, which will be deployed in the Ground-Based Midcourse Defense anti-ballistic missile system in Alaska around 2020.
Both radars have far greater ranges than current Aegis radars operated by Japan or the U.S.
Japan needs more powerful detection in order for its new longer-range interceptor missiles to provide more effective defence against North Korean launches and any potential threat from China. ($1 = 111.0700 yen) (Reporting by Tim Kelly Editing by Simon Cameron-Moore and Paul Tait)