Xi Jinping Sean Gallup/Getty Images In a break from decades of cautious nuclear policy, China has started a process of upgrading its ballistic missile capabilities into a more potentially dangerous form.

Foregoing a longstanding policy of maintaining a small nuclear force, Beijing has begun to place multiple miniaturized nuclear warheads atop ballistic missiles, The New York Times reports citing a report from the Department of Defense. Missiles with multiple warheads are harder to intercept as each warhead could break off from its delivery system and aim for a separate target.

China has had the capability of miniaturizing nuclear weapons since at least the 1990s, but has avoided the move so as to prevent a potential arms race. The new direction of Beijing's nuclear weapons stance comes under the direction of President Xi Jinping, who has made a series of bold moves to increase Chinese power both regionally and globally.

According to the Pentagon's report, Beijing has re-engineered the DF-5, a variation of the CSS-4 intercontinental ballistic missile shown below, to be outfitted with multiple warheads. China has approximately 20 DF-5s currently in silos across the country, each of which could target almost the entirety of the US.

Altogether, the modified DF-5s could launch upwards of 40 warheads at North America, according to the Times. This modification is intended to produce maximum destruction while increasing the chances that a Chinese warhead could get past US missile interceptors.

“They’re doing it,” Hans M. Kristensen of the Federation of American Scientists told the Times, “to make sure they could get through the ballistic missile defenses.”

The US has placed missile defenses in California and Alaska with the intention of defending against a possible North Korean strike. The US also operates joint Aegis and Patriot missile systems in South Korea, and is aiming at deploying the highly advanced THAAD missile interceptor to the peninsula as well.

Although these missile shields are aimed against North Korea, they could also block a Chinese strike.

The sudden modifications come at a time of increased tension throughout Asia. Japan and the US have strengthened and reaffirmed military ties, and the US is increasingly playing a large role in the South China Sea in the support of the Philippines. Both countries are involved in disputes with China over the South China Sea.

The aircraft carrier USS Nimitz (CVN 68), the guided-missile cruiser USS Chosin (CG 65), the guided-missile destroyers USS Sampson (DDG 102) and USS Pinkney (DDG 91), and the guided-missile frigate USS Rentz (FFG 46) operate in formation in the South China Sea. US Navy The timing of the DF-5 upgrades is likely a signal to the US that China is a quickly rising power in the region with only a limited tolerance for meddling in its backyard.

“This is obviously part of an effort to prepare for long-term competition with the United States,” Ashley J. Tellis, a senior associate at the Carnegie Endowment for International Peace, told the Times. "The Chinese are always fearful of American nuclear advantage.”