Islamic State has taken advantage of weak and collapsing governments to expand its reach, and remains determined to attack the United States, the top U.S. intelligence official said Tuesday.
The Sunni extremist group, which is based in Syria and Iraq but has affiliates in Africa and Asia, has become the "preeminent global threat," Director of National Intelligence James R. Clapper told the Senate Armed Services Committee in the annual "worldwide threats" hearing.
In what he called a "litany of doom," Clapper outlined a diverse list of threats facing the United States, including terrorism, cyberattacks sponsored by China and Russia, drug trafficking, missile tests by Iran and continued enrichment of nuclear material by North Korea.
Violent extremists are active in about 40 countries, he said, including seven that are experiencing a collapse of central government authority and 14 others threatened by conflict.
"There are more cross-border military operations underway in the Middle East since any time since the 1973 Arab-Israeli war," Clapper said.
He cited the conflicts in Iraq, Syria and Yemen as an example of the unstable conditions that Islamic State and other militant groups can use to expand and recruit and to plot attacks against the United States.
Clapper appeared later before the Senate Intelligence Committee, along with CIA Director John O. Brennan, FBI Director James B. Comey, National Security Agency Director Michael Rogers and Marine Lt. Gen. Vincent Stewart, director of the Defense Intelligence Agency, the Pentagon's top spy agency.
The intelligence officials said North Korea continues to enrich fissile material that could be used to fuel a nuclear bomb, adding to fears that the Pyongyang government is expanding its nuclear weapons program.
Over the weekend, Pyongyang launched a rocket that put a satellite into orbit in what U.S. officials believe was also a ballistic missile test.
But Clapper pushed back North Korea's claim Jan. 6 that it had tested a hydrogen bomb for the first time. He said the yield was "too low" for a thermonuclear device.
North Korea is developing a submarine-launched missile as well as a nuclear-tipped missile that could threaten the U.S., "although the system has not been flight-tested," Clapper said.
Cyberattacks continue to mount, he said, noting that Chinese cyberespionage has not let up since top officials from both countries met in September to hammer out an agreement on cybersecurity.
Russia also "is assuming a more assertive cyberposture" that indicates a desire to target critical infrastructure and spy on U.S. government operations, he warned.
He highlighted drug trafficking as a major concern. Heroin traffic across the southwestern border has doubled since 2010, Clapper said, and presents a major challenge to law enforcement.
In some cases, U.S. officials have intelligence about more shipments than the Border Patrol, Drug Enforcement Administration, U.S. Coast Guard and U.S. Navy have ships and personnel to interdict, he said.
Sen. Angus King, an independent from Maine, said his state has been particularly hard hit by the influx of cheap narcotics.
"A tidal wave of death is what we are talking about," King said. "This is killing people now in the United States in every state. It is not an abstract concern."
Amid the panoply of threats, officials returned to Islamic State as the most urgent concern.
The group's "leaders are determined to strike the U.S. homeland, beyond inspiring homegrown extremist attacks," Clapper said.
In 2014, the FBI arrested nine Islamic State supporters in the U.S., Clapper said, and last year that number "increased fivefold."
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