NHK has learned that Japan's largest opposition party has drafted a report against the government's plan to have the capability to mount counterstrikes on missile-firing sites and other enemy targets.

The report by the Constitutional Democratic Party says counterstrikes carry the strong risk of being misinterpreted as preemptive attacks.

The report says it is pragmatically difficult to discern whether enemies have started the process of attacking Japan.

The report says the party does not rule out the option of enhancing missile capability for self-defense. But it says Japan needs to declare that it will not initiate first strikes.

The report says Japan should not launch counterstrikes while exercising the right to collective self-defense in the event of armed attacks on allies such as the United States.

The plan to possess counterstrike capability appears in one of the three key defense documents the governments is working to revise.

The government's draft says counterstrikes should only be exercised with the minimum defense capability, and never be used preemptively.

The CDP's report also criticizes Prime Minister Kishida Fumio's plan to raise the country's annual defense budget to 2 percent of gross domestic product in fiscal 2027.

The report calls the plan unreasonable and proposes that the government should instead take a balanced approach to the national budget as a whole, including social security costs.

The party is expected to solicit the opinions of its lawmakers before finalizing the report.