"Our country's plan is (to acquire) 400 units" of the cruise missile, Kishida told the lower house budget committee without elaborating, citing the military sensitivity of the purchase.

Earlier this month, the defence minister said Japan has set aside 211.3 billion yen ($1.5 billion) to buy the missiles in the coming fiscal year, rather than dividing the procurement over several years.

Kishida's government wants to dramatically expand Japan's defence capacity in the face of China's growing military clout and nuclear-armed North Korea's unpredictable missile tests.

Russia's invasion of Ukraine has also stoked fears that China may move to take over Taiwan, a self-governed democracy claimed by Beijing.

Japan has a pacifist post-war constitution, which limits its military capacity to ostensibly defensive measures.

But last year it updated key security and defence policies, explicitly outlining the challenge posed by China and setting a goal of doubling defence spending to the NATO standard of two percent of GDP by 2027.