The Japanese Defense Ministry plans to set up a land-based Aegis missile defense system to address North Korea's missile threats, having decided to seek funding in the next fiscal year to cover the system design costs, a government source said Wednesday.

The ministry was planning to make a budgetary request to conduct "studies" over the installation of the so-called Aegis Ashore system, but has decided to move up the schedule amid continuing test-firing of ballistic missiles by Pyongyang, according to the source.

The ministry also plans to secure a budget to create a new "space unit" inside the Self-Defense Forces that will be tasked with protecting satellites used by Japan and the United States from attacks.

Japanese Defense Minister Itsunori Onodera is expected to explain the plans to the U.S. government during his current visit to Washington with Foreign Minister Taro Kono for talks with their U.S. counterparts Thursday.

In the budgetary request to be submitted by the end of August, the ministry will leave open the actual sum it is expecting for designing the Aegis Ashore program because of the need for consultations with the United States, the source said.

But the ministry plans to finalize the costs by the end of the year when the government will draw up the fiscal 2018 budget plan.

Under Japan's current multi-tier ballistic missile defense system, the Maritime Self-Defense Force's Aegis destroyers equipped with Standard Missile-3 interceptors are tasked with stopping missiles in the outer atmosphere.

If they fail, the Air Self-Defense Force's Patriot Advanced Capability-3 surface-to-air guided interceptors are the next line of defense against missile attack.

Aegis Ashore uses the same components fitted to MSDF Aegis destroyers, but the system is land-based. It is also easier for the SDF to prepare for missile intercepts because the system will be permanently installed.

The government is likely to start selecting candidate sites at the same time. The introduction of the new system will enable Japan to beef up its missile defense, but some critics say it could further increase tension in the surrounding region.

One estimate has shown that an Aegis Ashore unit costs about 80 billion yen ($728 million). It is unclear whether Japan can quickly start operating the system as it needs time to train SDF members in its use.

Following North Korea's threat last week to launch four ballistic missiles across Japan toward the U.S. territory of Guam, Japan has deployed the PAC-3 system to four prefectures in western region that the missiles could fly over.

The PAC-3 coverage is believed to be within a radius of several dozens of kilometers, with the system deployed in areas of particular importance.