Militant Chinese fishermen are flashing lasers at American military planes flying over the highly contested East China Sea, which is bordered by Japan, South Korea, and Taiwan as well as China.

Washington should consider the attacks, almost certainly directed by Beijing, as attempts to injure pilots and their crews. The American response, therefore, should be immediate in timing and devastating in effect, perhaps the only way to prevent the Chinese from eventually bringing down a U.S. plane.

Pentagon sources, speaking mostly without attribution, have revealed that since last September there have been almost two dozen known laserings of American military aircraft from fishing vessels and shore locations.

The most recent attacks occurred within the last two weeks, and the frequency is increasing.

The lasers used, although powerful, were commercially available. So far, none of the East China Sea attacks injured pilots.

A “military spokeswoman” told CNN that, in the words of the network, “the sources of these flashes are suspected to be Chinese.”

The attacks from the fishing boats are almost certainly the work of China’s part-time maritime militia, the so-called Little Blue Men.

Beijing on Friday denied responsibility, calling allegations “totally groundless and purely fabricated.”

The East China Sea incidents are reminiscent of other laserings in the South China Sea and Djibouti. In the first week of May, the Pentagon revealed the Djibouti attacks and blamed China for them, one of which caused minor eye injuries to two pilots of a C-130, a cargo plane.

There were four Djibouti attacks in all, three of them involving military-grade lasers located in the logistics area of China’s only overseas base.

The U.S. responded by delivering a formal diplomatic protest and requesting China to investigate. Beijing denied responsibility for these attacks as well.

The American response was obviously inadequate because the East China Sea incidents continued after Washington’s protest over the Djibouti attacks.

“There are really no innocuous explanations, just a really bad one and a somewhat bad one,” James Holmes of the Naval War College told The Daily Beast on Friday, referring to the East China Sea laserings .

“The really bad one,” as Holmes, speaking only in his personal capacity, explained, “is that these things are happening at the behest of the Chinese Communist Party leadership in Beijing, presumably through maritime militiamen embedded in the Chinese fishing fleet. That is, you have the agents of a foreign government carrying out direct attacks on U.S. military personnel operating in the maritime commons, or in this [East China Sea] case the airspace above. If one armed force attacks another—well, you know where that line of reasoning leads.”

And “the less bad interpretation”? It is possible that fishermen, armed with off-the-shelf lasers, are carrying out attacks on their own. Yet that is not much better than the first possibility. Holmes, holder of the War College’s first J. C. Wylie Chair of Maritime Strategy, notes that countries have an obligation to prevent nationals from engaging in warfare because sovereignty means a “government wields a monopoly on the legitimate use of force within its territory and within things that are legal extensions of its territory, in this case Chinese-flagged commercial vessels.”

It should be clear that the worse explanation is the correct one. For one thing, it is difficult to believe that Chinese fishermen can pick out American military aircraft from civilian ones without radar or other help. Moreover, state support is the best explanation for the increasing sophistication of the laserings.

And, as Arthur Waldron, the Lauder Professor of International Relations at the University of Pennsylvania, asked me on Friday, how many disgruntled fishermen dig down among their nets and find... a laser? “These are not isolated incidents,” he said. “They are part of a unified insane plan.”

“Insane”? It certainly seems so. And potentially lethal. Blinding pilots with lasers can bring down their planes.

Considering everything, the U.S. reaction to the Djibouti attacks was ineffectual. And perhaps it was purposefully so. Presumably, the Trump administration hoped the incidents were isolated and would end.

They have proven not to be isolated, unfortunately. The next move, therefore, is Washington’s. “Regardless of the form of response, the People’s Republic of China must understand that any further attacks on America will result in immediate and devastating consequences,” James Fanell, a leading China naval analyst, told The Daily Beast.

So what is “fierce and unequivocal,” as Fanell, who retired as director of Intelligence and Information Operations for the U.S. Pacific Fleet, puts it?

“Most importantly, what we do must not be tit for tat,” Waldron points out. “It must be ‘tit, tit, tit, tit, tit, tit, tit, tit, tit, tit, tit for tat,’ in other words, disproportionate, which is how you send the message.”

The U.S., of course, has a range of messages it can send, but there are two courses of action to consider adopting simultaneously.

The first order of business is to withdraw from the Protocol on Blinding Laser Weapons, the fourth protocol to the Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons Which May Be Deemed to Be Excessively Injurious or to Have Indiscriminate Effects.

Beijing feels free to violate its protocol obligations, so America’s participation is essentially a unilateral promise. Withdrawal would send a message that Washington will respond in kind if the situation warrants.

Second, the administration should end all military-to-military contacts. The Pentagon last month disinvited China to this year’s RIMPAC, the U.S. Navy-led multinational exercise off Hawaii, but the Chinese did not get the message and are still lasering American aircraft.

What’s the purpose of trying to win the goodwill of militant states taking actions that could have lethal consequences? Decades of such contacts have only helped Chinese generals and admirals improve their ability to target Americans.

Similarly, Washington needs to close China’s consulates and expel its diplomats—many of them. And to make the point, the administration should, before Beijing can retaliate, close American consulates in China and withdraw diplomats, a lot of them.

I don’t know the rationale for maintaining normal diplomatic relations with a nation in these circumstances, when it is engaging in attacks constituting acts of war. President Donald Trump needs to convince Chinese leaders that protecting Americans is far more important to him than maintaining relations with their regime.

Even without the laser attacks, there is cause for severe measures. China targeted American diplomats—or allowed the targeting of them—with sonic attacks directed at the Guangzhou consulate this year. The State Department has already withdrawn some diplomats—one with a minor brain injury—and dependents. It’s time to bring others home as a sign that such conduct is not acceptable and carries consequences.

Many may find such proposals too severe, but a slow ratcheting up of pressure has not in fact worked. Generous and hopeful American policies have, over the course of this decade and preceding ones, failed. Proportionality sounds responsible but actually encourages provocative behavior.

It’s unfortunate, but it’s time to deliver a response that makes Chinese leaders reel. Yes, this carries risk, but not doing anything effective is even more risky, especially in the long run. Unfortunately, the Trump administration, following decades-old China policies, is failing to disabuse Beijing of the notion it can harm Americans.

“My guess,” Holmes told me, “is we file routine diplomatic protests and leave it at that, until something bad happens and forces Washington’s hand.”

He’s probably right. Something bad is bound to happen.