SINGAPORE — Latest estimates by Western analysts put China’s stockpile at 240 warheads, with 175 in active mode and 65 in reserve or waiting to be dismantled because they are considered too old for use.

This is a small arsenal compared with those of the United States and Russia. The U.S. has declared that it has 5,113 active nuclear warheads. Russia is thought to have a similar number; it has indicated it will follow the U.S. and make a full disclosure after their latest treaty on strategic arms cuts has been ratified.

France said several years ago that it had no more than 300 warheads. Britain, the last of the five original nuclear weapons states, disclosed not long ago that it had 225 nuclear weapons, 160 of which are deployed.

Not only is China’s arsenal relatively small, but in normal circumstances the warheads are believed to be held in storage, not mated with delivery systems — mainly missiles of various kinds.

Beijing has also said repeatedly it will never be the first to use nuclear weapons in a conflict. Since the only other Asian nations known to have nuclear weapons are India and Pakistan (an ally of China), Asian countries without such weapons should be able to rest easy.

It may not be as simple as that. Unlike the other four nuclear powers in the treaty to prevent the spread of nuclear weapons, China has not disclosed the size of its arsenal and has increased its nuclear-capable weapons systems by roughly 25 percent in the past five years, according to the U.S. Defense Department.

China deploys about 130 land-based ballistic missiles that can carry nuclear warheads. There are six different types with differing ranges and payloads.

Those with the longest range — 7,200 to 13,000 kilometers or more — target the U.S. and Russia. But there are probably no more than 50 of these missiles carrying the same number of warheads. In the future, instead of single nuclear warheads, some of these missiles may carry three lighter-weight warheads, each able to strike separate targets.

However, the majority of China’s land-based nuclear missiles have ranges out to 3,300 kilometers, covering most of Asia as well as U.S. military bases in the region. The whole of India is within range of these missiles.

About 60 of them are DF-21 missiles, whose number has quadrupled since 2005. Some of the DF-21s are the C model, which can carry either a conventional high-explosive warhead or a nuclear one. This has prompted analysts to warn of the risks that might arise if the DF-21C was deployed in a conflict with India, which has a history of tension with China over their disputed border and other issues.

India would not be able to tell whether the missile was carrying a conventional or nuclear charge. It might well conclude that it was faced with a nuclear attack and respond in kind.

A similar risk of misunderstanding and escalation arises from China’s expansion of its cruise missiles. These missiles travel much more slowly than ballistic missiles, but they are highly accurate, skim low over the terrain, and are difficult to detect and shoot down.

The Pentagon says China has the most active land-based ballistic and cruise missile program in the world and that it is “developing and testing several new classes and variants of offensive missiles, forming additional missile units, qualitatively upgrading certain missile systems, and developing methods to counter ballistic missile defenses.”

The number of launchers for China’s DH-10 cruise missile, which has a range of more than 1,500 kilometers and is designed to hit land targets, has remained fairly constant at around 50. But the Pentagon reckons that the number of missiles for the launchers has risen by about 50 percent since 2009, to as many as 500.

Like the DF-21C ballistic missile, the DH-10 cruise missile could carry either a conventional or nuclear warhead. It is therefore a potential trigger for a devastating exchange of nuclear weapons in a regional conflict. Depending on prevailing winds, any radioactive fallout could spread across national boundaries in Asia. China wants to ensure that enough of its nuclear weapon systems survive to retaliate and inflict unacceptable damage if it is involved a nuclear war with either the U.S., Russia or India.

China worries that development by potential antagonists of more advanced technology for shooting down incoming missiles would undermine its nuclear deterrent. Hence its interest in more nuclear warheads and delivery systems.

However, India fears that China is modernizing and enlarging its precision- strike missile force to coerce its neighbors into resolving disputes on Beijing’s terms.

The optimistic view is that when China thinks it has a credible deterrent for each of its potential nuclear adversaries, it may join the U.S., Russia, Britain and France in being more open about its warhead stockpile and delivery systems.

At that point, China and India will need to negotiate a nuclear deal, assuming that India is confident in the deterrent power of its arsenal. India’s adversary, nuclear-armed Pakistan, will have to be brought into the negotiations.

The driving force in U.S.-Russia nuclear arms reduction and control is that transparency fosters predictability and minimizes the risk of a terrible war by miscalculation. A similar pact must be in the interests of China, India, Pakistan — and the rest of Asia.

The writer is a visiting senior research fellow at the Institute of South East Asian Studies in Singapore.

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