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The Obama administration unveiled its Nuclear Posture Review today. Reversing decades of policy, the long-awaited policy document declares the U.S. will limit the instances in which it will use nukes in the defense of the homeland. Moreover, it states the Pentagon will not develop a new generation of nuclear weapons.

Will the new policies make us safer? If there is one theme tying the parts of the Nuclear Posture Review together, it is that America will set an example for the rest of the world. And if the rest of the world follows, everyone—not just Americans—will be better off.

Unfortunately, the other major nuclear powers have not accepted President Obama’s lead. Russian President Dmitry Medvedev, for instance, announced in December that his nation will build new strategic offensive weapons and missiles. China, especially during this decade, has been increasing the size and sophistication of its arsenal at a fast pace.

The modernization of the Russian and Chinese stockpiles is especially troubling because the Pentagon’s arsenal is old: the average age of an American nuke is 26 years. The weapons can be refurbished, as the U.S. is now doing, but the credibility of America’s nuclear deterrent—and the nuclear umbrella protecting American allies—rests on the reliability of its warheads and bombs.

The problem is made more acute by the continual decrease in the number of deployed strategic weapons. This ups the importance placed on each such device working when it is needed.

Deployed American weapons will fall as the Obama administration pursues its goal of ridding the world of nukes. On Thursday in Prague, President Obama will sign the Start Follow-On Treaty, which replaces the landmark 1991 Strategic Arms Reduction Treaty, which expired in December.

In the new agreement the U.S. will accept parity with Russia in both deployed strategic weapons and launchers. Yet Russia and China call themselves “strategic partners” and for most of this decade have cooperated on military and diplomatic matters, often to the detriment of the U.S. China is not a party to the deal and has accepted no limits on missiles or warheads. So, if Moscow and Beijing draw closer, America could find itself in a situation of strategic inferiority. China, in short, can decisively tip the strategic balance against the U.S.

But even if the Dragon and the Bear never form a durable partnership, the Chinese arsenal, once so small American planners ignored it, becomes a major factor when the Start Follow-On Treaty is inked. In fact, it was a fundamental mistake not to have Beijing become part of the new arms control deal.

Furthermore, while President Obama negotiated the agreement with Russia, he took his eye off the critical issues of the day. He has, unfortunately, done little to disarm North Korea, stop Iran’s “atomic ayatollahs, or halt the Syrian nuclear weapons program. There are long-term goals and urgent tasks, and Washington needs to remember the principle of “first things first.” In pursuit of a grand strategy, the president has forgotten the rogues.

Gordon G. Chang is the author of "The Coming Collapse of China." He writes a weekly column at Forbes.com.

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