China is engaged in a “whole-of-government” effort to spread its influence around the world, undercut U.S. alliances and “foster new international norms that favor the authoritarian Chinese system,” the U.S. intelligence community concluded in a report released Tuesday that casts China as the most significant, long-term threat to the United States and its partners.

China’s leaders see competition with the U.S. “as part of an epochal geopolitical shift,” and view sanctions and other economic countermeasures enacted during the Trump administration “as part of a broader U.S. effort to contain China’s rise,” according to the intelligence community’s Annual Threat Assessment, which top officials will present to Congress this week.

The report focuses on crosscutting international issues — including the covid-19 pandemic, climate change and organized crime — that will challenge U.S. security and leadership, and it zeros in on Russia, North Korea and Iran as the other adversaries of greatest concern, with the latter poised to take new actions to develop a nuclear weapon.

China intends to at least double its stockpile of nuclear weapons in the next decade, pursue overseas military installations and bases and continue “securing what it views as its territory,” the report found. Chinese leaders will continue to press officials in Taiwan “to move toward unification,” and tensions will mount as Beijing steps up efforts to portray the country as isolated and dependent on the mainland for economic prosperity, it predicted.

China will seek to extend its influence by promoting its massive Belt and Road infrastructure initiative while trying to reduce waste and exploitative practices that have drawn international criticism, the report found. U.S. and other officials have accused China of entrapping developing nations with infrastructure projects they cannot afford, making them beholden to Beijing as a developer and a lender.

Intelligence officials will present their findings Wednesday and Thursday to the intelligence oversight committees in the Senate and House, marking the resumption of annual top-level testimony that was put on hold during the Trump administration.

Assessments of Iran’s ability to develop a nuclear weapon are likely to draw lawmakers’ scrutiny. The intelligence report found that Iran “is not currently undertaking” key activities necessary to produce a nuclear weapon, affirming an earlier judgment by the spy agencies at the same time the Biden administration seeks to reenter a nuclear deal with Iran.

But in a sign of how rapidly intelligence may be overtaken by events, hours before the report’s public release, a senior Iranian official announced a major jump in the country’s enrichment of uranium, to 60 percent purity, a defiant move that followed a blackout at an enrichment facility that Iran described as an act of sabotage.

The incident has been widely attributed to Israel.

After the Trump administration pulled the U.S. out of the nuclear agreement in May 2018, Iran abandoned some of its commitments and resumed some activities that exceed the limits set by the deal, the intelligence agencies state. It concluded that if Iran did not receive sanctions relief — which had been part of the original deal — officials would probably consider taking steps toward developing a nuclear device.

Enriching uranium above 60 percent was one such step, along with designing and building a new heavy water reactor, the report said. Last year, Iran’s parliament passed a law requiring construction of a new reactor.

The intelligence assessment arrives at a moment of high-stakes diplomacy. The U.S. and Iran began indirect talks last week in Vienna with an eye toward reviving the nuclear agreement.

White House press secretary Jen Psaki said “the United States was not involved in any manner” with the incident at Iran’s Natanz nuclear facility and said that Tehran had not “given any indication about a change” in its participation in negotiations over restarting the deal.

The intelligence report found that “Iran will present a continuing threat to U.S. and allied interests in the region” as it tries to erode U.S. influence and entrench its own. While Iran continues to be interested in building terrorist networks inside the United States, there is a greater threat to Americans abroad and from aggressive Iranian cyber attacks, which the country has aimed at its adversaries’ critical infrastructure, the report found. It pointed to multiple cyber attacks, for instance, between April and July 2020 against Israeli water facilities, citing press reports but not confirming the accounts.

The new report also describes Russia continuing its efforts to undermine U.S. influence and weaken relations with European allies.

Russia is seen as willing to form pragmatic alliances to suit its interests, including with the U.S., but continues to interfere in foreign affairs as it seeks to extend its own sphere of influence, the report states.

“Moscow is well positioned to increase its role in the Caucasus, intervene in Belarus if it deems necessary, and continue destabilization efforts against Ukraine.” Russian troops have been massing along that country’s border at their highest numbers in years.

But the intelligence agencies also “assess that Russia does not want a direct conflict with U.S. forces.” On Tuesday, Russia’s defense minister described the troop presence as a security drill in response to what he characterized as NATO aggression, saying the maneuvers would last another two weeks.

The U.S. intelligence report calls North Korea a “threat for the foreseeable future” because of its development of conventional military capabilities as well as nuclear weapons. While the Trump administration sought to reset relations with Pyongyang, the report concludes that North Korean leader Kim Jong Un “remains strongly committed to the country’s nuclear weapons” and finds that “the country is actively engaged in ballistic missile research and development.”