A Lockheed Martin LM-100J aircraft performs a display at the Farnborough Airshow, in Farnborough, Britain, July 16, 2018. REUTERS/Peter Nicholls

Japan said on Monday it had picked Lockheed Martin Corp to build a new powerful radar for two multi-billion dollar ground-based Aegis ballistic missile defense (BMD) stations meant to guard against North Korean missile strikes.

The decision is the latest sign that Japan is forging ahead with plans to reinforce its defenses despite a North Korean pledge to denuclearize. The purchase could also help Tokyo ease trade friction with Washington as its key ally threatens to impose tariffs on Japanese auto imports.

Although Japanese defense officials initially estimated the cost of the two Aegis Ashore batteries, slated for deployment from 2023, at around $2 billion, the final outlay will be at least double that, sources earlier told Reuters. Japanese media reports have put the cost of the two sites, which will include the Aegis air defense system, missile launchers and interceptors at around $6 billion.

The radar decision means Aegis Ashore can be added to a defense budget proposal slated for release next month ahead of any meeting between Japanese Prime Minister Shinzo Abe and 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, though during a visit to Tokyo in November he had 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(LRDR), which will be deployed in the Ground-Based Midcourse Defence anti-ballistic missile system in Alaska around 2020.

Both radars have far greater ranges than current Aegis radars operated by both Japan or the U.S.

Japan needs more powerful detection in order for its new longer-range interceptor missiles to provide more effective defense against North Korean launches and any potential threat from China.