Even as Chinese President Xi Jinping strides into the final Nuclear Security Summit today in Washington, D.C., he is considering a dangerous policy change: The Chinese military is asking to put its nuclear missiles on hair-trigger alert so they can be launched immediately upon detecting an incoming attack. President Barack Obama should encourage his counterpart to carefully consider such a change, because it would dramatically increase the risk of an accidental or mistaken nuclear launch against the United States or its allies.

China’s previous political leaders believed prudence demanded they wait and ride out a nuclear attack—should it come—before retaliating later at a time and place of their choosing. Their strategic patience was celebrated, at home and abroad, as a responsible expression of confidence that would discourage any enemy, including the United States, from attacking China with nuclear weapons in the first place.

But the current commander-in-chief is a new kind of leader. Xi appears to be a man in a hurry, and he has said he wants to make the Chinese military better prepared to fight and win wars, not simply prevent them.

Chinese military strategists expressed their desire to put the country’s nuclear weapons on high alert three years ago. Their language is labored but the meaning is clear:

When conditions are prepared and when necessary, we can, under conditions confirming the enemy has launched nuclear missiles against us, before the enemy nuclear warheads have reached their targets and effectively exploded, before they have caused us actual nuclear damage, quickly launch a nuclear missile retaliatory strike.

The strategists argue this is necessary to protect China from being disarmed of its roughly 150 nuclear missiles by a U.S. first strike, even a conventional one. China’s liquid-fueled ICBMs are fixed in identifiable silos and take time to prepare for launch. The military also has mobile solid-fueled ICBMs, but planners worry that mobility is less of a guarantee of survival than it used to be, given U.S. surveillance capabilities. A modest expansion is underway that includes replacing the large single warheads on the liquid-fueled missiles with two or three smaller ones. But the strategists worry that even this expansion will not be enough to guarantee an ability to retaliate.

Chinese engineers know U.S. ballistic missile defense isn’t ready for prime time. Given the countermeasures problem, it may never be. But the strategists aren’t engineers. They simply cannot believe the U.S. government would dump that much money into something that couldn’t work. China has been surprised by new military technology before. The strategists are wary the United States could scale up the size and capabilities of U.S. missile defenses. And they worry that even a marginally effective future BMD system might be able to ward off what few Chinese nuclear missiles survive a first strike to be launched in retaliation.

This is why the military strategists want Xi to put China’s nuclear missiles on high alert: they feel they need to be able to launch them before they are destroyed. And in their minds, at least, a Chinese launch on warning is still a second strike.

Moreover, they wonder, if the United States and Russia keep missiles on high alert, why shouldn’t China?

If Xi finds the case made by his military strategists compelling, he will be overlooking something important. The early warning systems needed to detect and confirm an incoming nuclear attack have been known to give false warning, especially in the early years of their operation. Even if the warning was real, would the Chinese operators be able to distinguish an incoming conventional strike from a nuclear strike? Would that matter if they thought the conventional strike was aimed at their nuclear forces? If China’s military stands up such a system and is given permission to launch on warning, it would create the risk of an accidental or mistaken nuclear launch against the United States.

Avoiding this risk should be a high priority for the White House, especially at a summit focused on nuclear security.

Xi may respond by encouraging Obama to take a harder look at the United States’ own nuclear weapons policy. The U.S. military currently keeps its 450 land-based ICBMs on alert and maintains the option to launch them quickly, even though it has submarine-launched long-range missiles that provide a survivable retaliatory force.

If the only outcome of Obama’s final nuclear security summit is that both nations see the folly of keeping nuclear forces on high alert, history will record it as a turning point in the effort to reduce the risk of nuclear war.