TOKYO (THE YOMIURI SHIMBUN/ASIA NEWS NETWORK) - In recent years, the term "exclusively defence-oriented policy" has been used on many occasions.

For instance, the Cabinet's security policy is often criticised for exceeding the "exclusively defence-oriented policy."

The Defence Ministry's annual white paper titled "Defence of Japan" refers to the policy as one of the pillars of the country's fundamental defence policy, spelling out: "The exclusively defence-oriented policy means that defensive force is used only in the event of an (armed) attack, that the extent of the use of defensive force is kept to the minimum necessary for self-defence, and that the defence capabilities to be possessed and maintained by Japan are limited to the minimum necessary for self-defence.

"The policy including these matters refers to the posture of a passive defence strategy in accordance with the spirit of the Constitution."

The statement is usually interpreted to mean that Japan would (1) refrain from initiating a preemptive military strike on any foreign country, (2) use its defence capabilities only within its territorial land and waters and (3) possess no long-range offensive weapons.

When looking into the extent of the defence capabilities Japan should have, it is worth remembering the famous standpoint on the legal limitations of such capabilities elucidated in February 1956 by then Prime Minister Ichiro Hatoyama at the Cabinet Committee of the House of Representatives.

"It is unreasonable to think that the purpose of the Constitution is that Japan has to sit and wait for death when it comes under attack by missiles and other weapons," Hatoyama said.

"As far as it is recognised that (Japan) has no other means to defend itself from an attack by missiles and other weapons, striking the (enemy's) missile base and the like is, in legal terms, within the right of self-defence and, therefore, permissible."

This policy has been upheld to this date.

International law now prohibits nations from using armed force, except in self-defence.

As the U.N. Charter stipulates that the right of self-defence can be exercised if an enemy attack is "actual or imminent," Hatoyama's statement in the Diet remains consistent with international law.

Compared with Hatoyama's interpretation and the global norm of international law, the scope of self-defence adhered to by the Japanese government of today is far more narrowly defined.

The exclusively defence-oriented policy is also referred to as Japan's basic national principle.

But what is a basic national principle? Is it above or below the Constitution?

Needless to say, it is below the supreme law.

Given that the Constitution has an article about amending it, a basic national principle, too, should be subject to amendment.

However, in reality, the principle in question has no such clause.

Above all, no definite provision is in place to even define what a national principle is.

As such, a national principle just means a basic policy. We should then stop using the term "basic national principle" without giving due consideration to the content of and procedures for such an important matter to be determined.

When Hatoyama unveiled his security standpoint more than 60 years ago, Japan faced no serious threat from its neighbours.

Now, North Korea not only possesses a nuclear arsenal and missiles, but also repeats threatening language against Japan.

Nonetheless, Japan has no capability for striking an enemy's bases.

On Jan 26, 2017, Prime Minister Shinzo Abe told the Diet that Japan has no weaponry for launching an attack on an enemy's bases and had no such plan in sight.

Many Japanese expect the United States to counterstrike against the enemy.

But is there a guarantee that the U.S. forces will stage such a counterstrike in line with Japan's expectations?

No armed attack is without risks.

So, when Japan keeps itself from such risks, is it still possible to always expect the United States to carry out a counterattack for us?

The Japan-U.S. Security Treaty provides each party with the rights for revision and even termination - the United States is entitled to ditch the treaty if it wants to.

What will Japan do in such a worst-case scenario?

The Japanese government says a missile defence (MD) system will deal with North Korea's possible missile attacks.

But the effectiveness of missile defence is highly doubtful.

No 100 per cent perfect MD system is conceivable. Rather, it is possible that the system's accuracy rate of hitting incoming enemy missiles is very low.

Considering the number of missiles North Korea is thought to have already deployed, the existing MD system in and around Japan is far from capable of hitting every last missile.

The accuracy rate will clearly decline if the North opts to simultaneously fire multiple missiles, including decoys to confuse the interception efforts.

Moreover, the MD system is expensive. It is true that Japan now cannot afford to spend money for such costly but unreliable defence infrastructure.

In October 2017, I wrote in this column that I opposed any discussion that focused simply on Japan's ability to embark on a preemptive attack on an enemy state.

Striking a specific enemy base or bases requires a considerably high level of intelligence-gathering expertise.

Otherwise, a preemptive offensive is difficult.

However, it would be another story once Japan actually comes under attack.

In that case, the exact location of the enemy base to be targeted in a counterstrike would already be known.

If the enemy has already begun raiding Japan, it will be natural for our country to attack the base - as well as other bases - in the enemy state to forestall further operations by it.

For the same reason, it will also be natural for Japan to resort to further military operations to destroy the relevant systems used by the enemy state for its campaigns against Japan.

The targets of Japan's counteroffensive should also include the enemy's leaders - as in the case of what South Korea calls a "decapitation operation" - and its military facilities.

Some people fear that the existence of a counterstrike ability may lead to a preemptive strike. This is a pointless concern.

For Japan, there would be nothing to gain if it instigates military operations against any of its neighbouring countries.

Further, given that most of its neighbours have nuclear weapons, no leader in Japan could be so ill-advised as to think of ordering a preemptive offensive.

To put it differently, a political declaration by a sitting Japanese prime minister that Japan will not initiate any preemptive attack will be sufficient as a constraint against such an operation.

With all of this in mind, I have a strong objection to the way constitutionalism has been treated in recent years by certain groups of people led by constitutional scholars.

Constitutionalism originally rests on the idea of restraining the government in exercising its power. That is fine.

Nevertheless, in recent years, certain people have advocated constitutionalism as a lever to go farther to constrain government action as much as possible.

However, the nation must survive international competition.

Under such circumstances, we entrust the government to protect our lives and safety.

To that end, it is necessary for the government to be given a certain level of power and discretion. Can the government live up to our trust when it is hedged around with various constraints?

For example, if every military action needs Diet approval in advance, an unrealistic choice for the security of the country, the government cannot act swiftly and adequately.

In such a case, there is a strong possibility that Japan would be invaded and the safety of its people placed in jeopardy.

Afterward, the government, while admitting its responsibility to act in such an emergency, would excuse itself for having done nothing to defend the nation and its population because of the lack of Diet-approved power to do so.

In a nutshell, an excessive state of constitutionalism would make it difficult to hold those in power accountable for their failure to act.

Those who advocate a strict application of constitutionalism rather seem to have excessively high trust in politicians and bureaucrats.

It is necessary to vest politicians and bureaucrats with sufficient authority and make them strictly responsible for failure to perform official duties.

But those advocates expect lawmakers and bureaucrats to work for them anyway without giving them sufficient power.

Now, let me move quickly toward a conclusion.

My proposal is that the exclusively defence-oriented policy be redefined more closely in line with Hatoyama's standpoint.

My proposal is accompanied by the following policy choices.

Japan will not resort to a preemptive strike, an approach that is more limited than what Hatoyama said.

But if it is attacked, it will carry out a counterstrike beyond its territory and territorial waters to destroy the enemy's base where the campaign against Japan has been launched, as well as other bases and the decision-making system of the foe that implemented the operation against our country.

Japan will possess the weapons necessary to press ahead with such a counteroffensive, while refraining from arming itself with weapons of mass destruction that could lead to indiscriminate bloodshed.

Japan's prime minister will declare that the government will not launch a preemptive strike, and if the pledge is broken, he or she will take responsibility by resigning.

What I just proposed is still overwhelmingly peace-loving in nature, when compared with other major countries in the world.

As with the Hatoyama statement, my proposal does not infringe on the Constitution at all.

What is more, what is envisaged in my proposal may be less costly than a missile defence system.

Currently, the Abe administration is making efforts to revise the Constitution.

However, even if the Constitution is amended as Abe has proposed, the area of activity and authority of the Self-Defence Forces, according to his explanation, will not be enlarged.

On the other hand, the change in the definition of the exclusively defence-oriented policy that I have proposed will expand the SDF's area of activity to a far greater extent.

If both the proposed revision of the Constitution and the redefinition of the exclusively defence-oriented policy are realised, it would be an excellent outcome.

If we are in a situation where we will have no choice but to go ahead with either of them, I am sure that political resources should be used for redefining the country's principle of the exclusively defense-oriented policy.

The writer is a professor emeritus at the University of Tokyo, specialising in Japanese political and diplomatic history.

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