WASHINGTON — China’s effort to expand its growing influence represents one of the largest threats to the United States, according to a major annual intelligence report released on Tuesday, which also warned of the broad national security challenges posed by Moscow and Beijing.

The report does not predict a military confrontation with either Russia or China, but it suggests that so-called gray-zone battles for power, which are meant to fall short of inciting all-out war, will intensify with intelligence operations, cyberattacks and global drives for influence.

The assessment highlights the opportunities and challenges for the Biden administration. Iran, for instance, has not advanced its work on a nuclear weapon, potentially giving President Biden some room to maneuver. But it paints a grim prognosis for a peace deal in Afghanistan, a day before Mr. Biden is set to announce that he will withdraw American forces by September. Critics could use the report to suggest that the president is ignoring intelligence agencies’ predictions as he pushes forward with the drawdown.

While much of the report describes traditional national security challenges, it also gives far more attention to climate change and global health than previous threat assessments have done. That shift reflects a pledge by the Biden administration’s top intelligence officials to focus more on such nontraditional challenges.

The report puts China’s push for “global power” first on the list of threats, followed by Russia, Iran and North Korea. There are typically few broad revelations in the annual reports, which are a collection of declassified assessments, although the intelligence agencies’ ranking of threats and how they change over time can be telling.

“Beijing, Moscow, Tehran and Pyongyang have demonstrated the capability and intent to advance their interests at the expense of the United States and its allies, despite the pandemic,” the report said. “China increasingly is a near-peer competitor, challenging the United States in multiple arenas — especially economically, militarily and technologically — and is pushing to change global norms.”

China’s strategy, according to the report, is to drive wedges between the United States and its allies. Beijing has also used its success in combating the coronavirus pandemic to promote the “superiority of its system.”

The report predicts more tensions in the South China Sea, as Beijing continues to intimidate rivals in the region. It also predicts that China will press the government of Taiwan to move forward with unification and criticize efforts by the United States to bolster engagement with Taipei. But the report stopped short of predicting any kind of direct military conflict.

“We expect that friction will grow as Beijing steps up attempts to portray Taipei as internationally isolated and dependent on the mainland for economic prosperity, and as China continues to increase military activity around the island,” the report said.

It also foresees China at least doubling its nuclear stockpile over the next decade. “Beijing is not interested in arms-control agreements that restrict its modernization plans and will not agree to substantive negotiations that lock in U.S. or Russian nuclear advantage,” the report said.

China uses its electronic surveillance and hacking abilities to not only repress dissent domestically but also to conduct intrusions that affect people beyond its borders, the report said. The country also represents a growing threat of cyberattacks against the United States, and the intelligence agencies assess that Beijing “at a minimum, can cause localized, temporary disruptions to critical infrastructure within the United States.”

There are few surprises in the report’s assessment of Russia. It makes clear that although many view Moscow as a declining power, American spy agencies still consider it a pre-eminent threat, pointing to a Russian supply chain hacking that created vulnerabilities in some 18,000 computer networks worldwide. The assessment said that while Russia would avoid direct conflict with the United States, it would use influence campaigns, mercenary operations and military exercises to advance its interests and undermine those of its rival.

Mr. Biden spoke to President Vladimir V. Putin of Russia on Tuesday. While Mr. Biden raised the prospect of a summit with Mr. Putin, he pressed him on the recent buildup of Russian troops on Ukraine’s border and in Crimea. The report said that Russia would seek opportunities for pragmatic cooperation but that it would also press the United States not to interfere in the domestic concerns of Ukraine and other countries of the former Soviet Union.

While cyberthreats have traditionally been a separate section of the report, this year’s assessment made more of an effort to weave such attacks into the broader threat picture, examining both China’s and Russia’s record of intrusions against the United States.

The intelligence agencies are right to refocus the threat assessment on Russia and China, said Representative Adam B. Schiff of California, the chairman of the House Intelligence Committee.

“China’s a rising power and a rising challenge,” said Mr. Schiff, a Democrat, whose committee drafted a report last year calling for more resources to be devoted to China. “Russia is a dying power. It poses the threat of a kind of wounded animal that is dangerous because it’s wounded and backed into a corner.”

This year’s report offers a far more robust discussion of the national security implications of climate change, whose threats, for the most part, are long term, but can also have short-term consequences, the report said.

“This year, we will see increasing potential for surges in migration by Central American populations, which are reeling from the economic fallout of the Covid-19 pandemic and extreme weather, including multiple hurricanes in 2020 and several years of recurring droughts and storms,” the report said.

It adds that the economic and political implications of the coronavirus would reverberate for years, predicting that the economic damage would worsen instability in a few countries, though it does not name them.

Combined with extreme weather caused by climate change, the report says the number of people worldwide experiencing acute hunger will rise to 330 million this year from 135 million. The report says that the pandemic has disrupted other health services, including polio vaccinations and H.I.V. treatments in Africa.

Typically, the director of national intelligence delivers the threat assessment to Congress and releases a written report alongside it. But no declassified assessment was issued last year, as the Trump administration’s intelligence agencies sought to avoid angering the White House.

In 2019, Dan Coats, then the director of national intelligence, delivered an analysis of threats from Iran, North Korea and the Islamic State that was at odds with President Donald J. Trump’s views. The testimony prompted Mr. Trump to lash out on Twitter, admonishing his intelligence chiefs to “go back to school.”

Avril D. Haines, the director of national intelligence; William J. Burns, the C.I.A. director; and other top intelligence officials will testify about the report on Wednesday and Thursday.

“The American people should know as much as possible about the threats facing our nation and what their intelligence agencies are doing to protect them,” said Ms. Haines, whose office released the report.

David E. Sanger contributed reporting.