The Director of US National Intelligence Avril Haines has cited Iran's contribution to instability in the Middle East as she testified at a public congressional "Worldwide Threats" hearing.
Haines also told the Senate Intelligence Committee that China is an "unparalleled" priority.
She described China as increasingly "a near-peer competitor challenging the United States in multiple arenas."
Federal Bureau of Investigation Director Christopher Wray said his agency opens a new investigation linked to China every 10 hours.
Central Intelligence Agency Director William Burns, National Security Agency Director General Paul Nakasone and Defense Intelligence Agency Director Lieutenant General Scott Berrier also testified.
Burns said nearly a third of the CIA's workforce is focused on cyber issues.
Haines also cited Russian efforts to undermine US influence, Iran's contribution to instability in the Middle East, global terrorism and potential North Korean efforts to "drive wedges" between Washington and its allies as significant threats.
The appearance by Haines and the other intelligence directors was the first such public "Worldwide Threats" hearing since January 2019.
The same officials will appear before the House Intelligence Committee on Thursday.
Before the hearings, the intelligence community published its annual threat assessment, which said China was pursuing a “whole-of-government” effort to spread its influence around the world, undercut US alliances and “foster new international norms that favor the authoritarian Chinese system.”
Russia is likely to continue developing its military and cyber capabilities while also seeking "opportunities for pragmatic cooperation with Washington on its own terms,” said the report.
North Korea, meanwhile, remains committed to nuclear power and poses an increasing risk to the US and to the region. Iran, too, presents a threat despite its weakening economy through both its conventional and unconventional military strategies, including its network of proxies.