The party’s security panel said in the proposal given to Prime Minister Shinzo Abe. “We should not waste any time to strengthen our ballistic missile defense.”

Japan’s ruling party urged the government on Thursday to consider arming the country with more advanced and offensive capability, such as striking enemy targets with cruise missiles, further loosening the self-defense-only military posture Japan has had since the end of World War II.

The Liberal Democratic Party’s council on defense policy urged the government to immediately start studying ways to bolster Japan’s capability to intercept missiles with a system such as the Terminal High-Altitude Area Defense, or THAAD system, that the US and Seoul have agreed to install in South Korea.

The panel cited a “new level of threat” from North Korea, which fired four missiles this month, three of them landing inside Japan-claimed exclusive economic waters.

“North Korea’s provocative acts have reached a level that Japan absolutely cannot overlook,” the party’s security panel said in the proposal given to Prime Minister Shinzo Abe. “We should not waste any time to strengthen our ballistic missile defense.”

The panel noted that North Korea’s recent missile launches have shown advancing technology, with a capability to launch from a mobile facility or submarine, use solid fuel, as well as fired to a high-altitude trajectory which makes it harder to trace and respond.

With higher levels of threat coming from North Korea, Japan should now consider possessing “our own capability of striking back an enemy base, with cruise missiles for instance, to further improve deterrence and response as part of the Japan—US alliance,” according to the proposal.

The panel said the government should immediately start studying a possibility of introducing THAAD and the shore-based Aegis missile defense system, among other equipment, while pursuing upgrades to two existing missile defenCe systems ship-to-air SM—3 interceptors and the ground-based PAC—3. It said necessary budget should be allocated for the possible new options.

Japan has maintained that its right to strike a foreign base in case of an imminent attack is not banned under the constitution and hawkish lawmakers have studied a possibility, though it has never been proposed as a realistic option.

Former defence minister Itsunori Onodera, who headed the defense policy council, told Mr. Abe that Japan needs to be prepared for being targeted by multiple missiles.

“Our proposal is about how we can fight back and stop the other party from firing a second missile, instead of making a pre-emptive strike,” he said.

Mr. Abe said he takes the report seriously and will cooperate with the party to improve Japan’s ballistic missile response.

Japan is bound by its postwar pacifist constitution, and the proposal does not call for a first-strike capability. Japan since its World War II defeat has limited its military to self-defence, while relying on the US “nuclear umbrella” and its 50,000 troops stationed in Japan under a bilateral security alliance as deterrence.

Mr. Abe has stretched those restrictions by easing a self-imposed ban on weapon exports and reinterpreting the war-renouncing constitution to allow Japan’s military to defend allies under attack. Japan and its top ally, the U.S., also revised their defense guidelines, giving Japanese Self Defense Force a greater role.