Japanese Defense Minister Itsunori Onodera says the Aegis Ashore land-based missile defense system will be nearly 70 percent more expensive than initially estimated.
Onodera told reporters on Monday that the government has selected the radar Lockheed Martin SSR for the missile interception system.
The radar was proposed by the US government and the aerospace maker.
The government had estimated that one Aegis Ashore unit would cost about 720 million dollars. But Onodera disclosed that the cost is likely to rise to 1.2 billion dollars because the newest, most sophisticated radar was chosen.
The Japanese government plans to deploy 2 Aegis Ashore units -- one in the western city of Hagi and another in the northern city of Akita -- to intercept North Korean ballistic missiles.
It is expected to take 6 years to deploy the units after signing the contract.
But there are calls to reconsider the deployment in the wake of the US-North Korean summit last month.
Onodera said the Aegis Ashore will drastically improve Japan's missile defense capabilities. He also said the cost is not final, and that the government will scrutinize it at every phase.