Diet deliberations on defense spending remain low-key. The fiscal 2018 state budget draft is expected to clear the House of Representatives this week, meaning the budget could be passed without substantive discussions on the nation’s security policy.

One issue that requires more active debate is the land-based Aegis Ashore missile defense system, which Japan will deploy to counter North Korea’s nuclear weapons and missiles. Two consecutive rounds of interception tests using the missile system, which Japan and the United States jointly developed, ended in failure.

The introduction of two Aegis Ashore systems will cost taxpayers approximately 200 billion yen. Debate on the price-performance ratio of the systems is indispensable, but so far, no in-depth discussions have been held.

Japan procures cutting-edge defense equipment from the United States under the so-called foreign military sales (FMS) contracts. Japan is supposed to make payments in advance of procuring defense equipment from the United States according to costs estimated by Washington. However, the United States has failed to fully return the excess Japan has paid — which amounts to billions of yen a year.

The FMS system is one of the factors behind the high prices of defense equipment Japan procured from the United States. Nevertheless, the Diet has failed to thoroughly debate how to improve the procurement system.

In particular, serious questions remain about the lack of in-depth discussions on the introduction of long-range cruise missiles. With China’s maritime advancement in mind, the Defense Ministry seeks to beef up defense of Japan’s remote islands. However, the three types of cruise missiles that Japan plans to introduce are ones that could be used to hit missile bases in North Korea in contingencies. Their total cost is 2.2 billion yen.

While maintaining that attacking an enemy’s bases is within the bounds of self-defense, Japan has in the past refrained from introducing equipment necessary for such attacks, from the viewpoint of the country’s exclusively defensive policy under the war-renouncing Constitution.

Prime Minister Shinzo Abe told a House of Representatives Budget Committee session on Feb. 14 that the introduction of long-range cruise missiles “isn’t aimed at attacking enemy bases,” but added that a policy limited to defense “is extremely difficult when considered purely as a defense strategy.” He was apparently trying to emphasize that the current policy was placing serious restraints on Japan’s defense, as military technology has advanced and the security environment surrounding the country has become increasingly severe.

The question of how to interpret the limitations of Japan’s defense-only policy is an important one. Yet opposition parties do not appear to have keenly delved into the issue in Diet discussions. This is apparently because the opposition Democratic Party split last year and time allotted to opposition parties for questioning in the Diet has been reduced. It is true that the Diet faces other outstanding issues, including reform of the way people work, but it is obvious that opposition parties have failed to raise questions about security policy.

The Diet is the only organization that can judge what kind of defense capabilities Japan should adopt and whether such capabilities are consistent with Japan’s purely defensive policy through deliberations on the budget draft. Each and every member of the Diet should be aware of their responsibility to clarify points of contention and engage in thorough debate.