WASHINGTON -- North Korea has expanded a uranium enrichment facility and restarted a plutonium reactor that could start recovering spent fuel in weeks or months, the U.S. intelligence chief said Tuesday in delivering the annual assessment by intelligence agencies of the top dangers facing the country.

Director of National Intelligence James Clapper said that Pyongyang had made progress on its intentions announced in 2013 to refurbish and restart nuclear facilities, to include the uranium enrichment facility at Yongbyon and its graphite-moderated plutonium production reactor, which was shut down in 2007.

"We assess that North Korea has followed through on its announcement by expanding its Yongbyon enrichment facility and restarting the plutonium production reactor," Clapper said in an opening statement to the Senate Armed Services Committee. "We further assess that North Korea has been operating the reactor long enough so that it could begin to recover plutonium from the reactor's spent fuel within a matter of weeks to months."

CBS News foreign affairs analyst Pamela Falk reported that Russian U.N. Ambassador Vitaly Churkin said the possibility of resuming six-party talks with North Korea was not probable.

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"I wish I had a magic wand," Churkin told reporters. "Unfortunately they have been unreasonable, they have been trying to challenge the entire international community."

François Delattre, France's U.N. Ambassador, called the North Korean move a "new, outrageous provocation from the North Korean regime and a blatant violation of all concerned resolutions of the Security Council that is a grave threat to international peace and security. The entire international community has condemned this action," he said.

He called for "a quick, firm, and severe response from the Security Council" and for it to come "The sooner the better, the firmer the better."

Clapper said that Islamic militants will continue plotting against U.S. interests overseas and that homegrown attacks will continue to pose the most significant threat from violent extremists to Americans at home.

"The perceived success of attacks by homegrown violent extremists in Europe and North America, such as those in Chattanooga and San Bernardino, might motivate others to replicate opportunistic attacks with little or no warning, diminishing our ability to detect terrorist operational planning and readiness," he said.

"ISIL involvement in homeland attack activity will probably continue to involve those who draw inspiration from the group's highly sophisticated media without direct guidance from ISIL leadership," he said using an acronym for the militant group.

Clapper also said Iran remains the top state sponsor of terrorism, al-Qaeda-linked groups remain resilient and theU.S. will continue to see cyber threats from China, Russia and North Korea. Clapper said U.S. information systems, controlled by the U.S. government and American industry, are vulnerable to cyberattacks from Russia and China.

North Korea "probably remains capable and willing to launch disruptive or destructive cyberattacks to support its political objectives," he said. Moscow "is assuming a more assertive cyber posture" that is based on its willingness to target critical infrastructure and carry out espionage operations even when those operations have been detected and under increased public scrutiny, Clapper said.

Russia's cyber operations are likely to target U.S. interests in part to underpin its intelligence gathering to support Russia's moves in the Ukraine and Syrian crises, he said.

Clapper said China selectively uses cyberattacks against targets Beijing believes threaten Chinese domestic stability or regime legitimacy. "We will monitor compliance with China's September 2015 commitment to refrain from conducting or knowingly supporting cyber-enabled theft of intellectual property with the intent of providing competitive advantage to companies or commercial sectors," he said.