China is alone among the original nuclear weapons states to be expanding such deterrent forces, the US-China Economic and Security Review Commission said in a draft of its 2012 report to the US Congress.
Beijing is "on the cusp of attaining a credible nuclear triad of land-based intercontinental ballistic missiles, submarine-launched ballistic missiles, and air-dropped nuclear bombs," the report says.
China has had a largely symbolic ballistic missile submarine capability for decades but is only now set to establish a "near-continuous at-sea strategic deterrent," the draft said.
The deployment of such a hard-to-track submarine-launched leg of China's nuclear arsenal could have significant consequences in East Asia and beyond. It also could add to tensions between the United States and China, the world's two biggest economies.
For instance, any Chinese effort to ensure a retaliatory capability against a notional US nuclear strike "would necessarily affect Indian and Russian perceptions about the potency of their own deterrent capabilities vis-a-vis China," the report said.
China is party to many major international pacts and regimes regarding nuclear weapons and materials. But it remains outside of key arms limitation and control conventions, such as the New Strategic Arms Reduction Treaty signed in April 2010 and the 1987 Intermediate-Range Nuclear
Forces Treaty. The United States historically has approached these bilaterally with Russia.
Congress should require the US State Department to spell out current and planned efforts to integrate China into existing and future nuclear arms reduction, limitation, and control discussions and agreements, the draft said.
In addition, Congress should "treat with caution" any proposal to unilaterally, or in the context of a bilateral deal with Russia, reduce operational US nuclear forces without clearer information being made available to the public about China's nuclear stockpile and force posture, it said.
A spokesman for the Chinese embassy in Washington, Geng Shuang, did not immediately respond to a request for comment.
The Pentagon declined to comment directly on China's march toward creating a credible nuclear "triad" involving strategic bombers, intercontinental ballistic missiles and submarine-launched ballistic missiles.
"We monitor carefully China's military developments and urge China to exhibit greater transparency regarding its capabilities and intentions," Lieutenant Colonel Monica Matoush, a Defense Department spokeswoman, said by email.
Any assessment of China's ability to have a nuclear triad would be an intelligence matter and likely be classified in nature, she added.
The final version of the report is to be released next Wednesday by the US-China commission, a 12-member bipartisan group set up in 2000 to report to US lawmakers on security implications of US-China trade.
(Editing by Lisa Shumaker)