WASHINGTON — Eight months after Russia’s invasion of Ukraine and as China pushes to increase its nuclear, space and cyberforces, the Pentagon outlined a sweeping new strategy on Thursday that called for more robust deterrence at an increasingly tense moment in international security.
The document, the National Defense Strategy, which also includes reviews of the U.S. nuclear arsenal and missile defenses, has been circulating for months in classified form on Capitol Hill. The unclassified version published on Thursday is devoid of much specificity about how the Pentagon will shift its weapons and personnel to fit a new era of heightened superpower competition.
The last national defense strategy, published in 2018 by the Trump administration, was the first since the end of the Cold War to refocus U.S. defenses on what it called the twin “revisionist” powers of China and Russia. President Biden’s document builds on that theme but distinguishes between describing China as a “pacing” technological and military challenger, and Russia as an “acute” threat but a declining power.
It prioritizes threats to the country, maps out the military’s response in broad terms and guides Pentagon policy and budget decisions on a range of issues, such as what weapons to develop and the shape of the armed forces.
But its contrast to the last document issued by a Democratic president, Barack Obama, is stark. Mr. Obama’s strategy — issued with Mr. Biden, who was the vice president at the time — had ambitions for drastically diminishing the role of nuclear weapons in U.S. defenses and described shared efforts with China and Russia to contain North Korea and dissuade Iran from building nuclear weapons.
The new document describes a Russia armed with 2,000 tactical nuclear weapons and not bound by any treaty that limits the number, raising “the possibility it would use these forces to try to win a war on its periphery or avoid defeat if it was in danger of losing a conventional war.”
That is exactly what President Vladimir V. Putin of Russia has threatened.
The document also describes an effort by China to rapidly expand its nuclear arsenal to about 1,000 strategic weapons in coming years. “The current and growing salience of nuclear weapons in the strategies and forces of our competitors heightens the risks,” it says.
Threats from Iran, North Korea and terrorist groups like Al Qaeda and the Islamic State persist — and new challenges, like global climate change, are emerging. But the strategy document focuses heavily on China and Russia.
“The P.R.C. and Russia now pose more dangerous challenges to safety and security at home, even as terrorist threats persist,” the document said, using the abbreviation for the People’s Republic of China. It noted that both rivals have deployed space weapons that could disrupt GPS and other “space-based capabilities that support military power and daily civilian life.”
The Pentagon sent a classified version of the defense strategy to Congress in March; at that time it also released a bare-bones, two-page fact sheet that summarized the document’s contents. The release on Thursday of the unclassified version, running nearly 80 pages, was delayed until the White House made public its overarching national security strategy this month.
In that document, Mr. Biden made clear that over the long term he was more worried about China’s moves to “layer authoritarian governance with a revisionist foreign policy” than he was about a declining, battered Russia.
The Pentagon document cited several new challenges to strategic stability, including hypersonic weapons, advanced chemical and biological weapons, and new and emerging warheads and delivery systems for conventional arms and tactical nuclear weapons.
That threat became more evident in the past several weeks amid signs that Mr. Putin’s commanders may be preparing the ground for a sharp escalation in the war in Ukraine. Mr. Putin has threatened to use tactical nuclear weapons.
While U.S. officials said that there was no change in Russia’s nuclear posture, and that they believed no decision had been made to use a tactical nuclear weapon, they made clear that a move in that direction was their central concern.
The concerns reflect what the defense strategy calls “the acute threat posed by Russia, demonstrated most recently by Russia’s unprovoked further invasion of Ukraine.”
In response, the document said, “The department will focus on deterring Russian attacks on the United States, NATO members and other allies, reinforcing our ironclad treaty commitments, to include conventional aggression that has the potential to escalate to nuclear employment of any scale.”
The Pentagon has already taken several steps to bolster its deterrence in Europe. The United States now has just over 100,000 troops in the continent, up more than 20,000 forces since before the Ukraine war started in February.
Mr. Biden announced in June that the United States would establish a permanent military base in Poland. It is the first time the country has done so anywhere on NATO’s eastern flank, which until now has had only a rotating troop presence.
The Pentagon will also maintain an additional rotational Army brigade in Romania, increase rotational troop deployments in the Baltic countries, deploy two squadrons of F-35 aircraft to Britain, station additional air defense units in Germany and Italy, and seek to increase the number of destroyers stationed in Spain.
If Russia was the Pentagon’s immediate security challenge, China was its long-term concern, or “pacing challenge,” the strategy document said.
“The most comprehensive and serious challenge to U.S. national security is the P.R.C.’s coercive and increasingly aggressive endeavor to refashion the Indo-Pacific region and the international system to suit its interests and authoritarian preferences,” the document said, criticizing China for its “increasingly provocative rhetoric and coercive activity towards Taiwan.”
To counter China’s influence, the document said that the Pentagon would continue to build up basing and coordinate with the State Department to expand U.S. access in the region.