A U.S. senator urged the administration of President Barack Obama on Wednesday to act immediately to rein in North Korea, calling leader Kim Jong-un a "forgotten maniac" seeking nuclear weapons and cyberwar capabilities while torturing his own people.

Sen. Cory Gardner made the appeal in an article to the Wall Street Journal, stressing that while the U.S. is preoccupied with problems in the Middle East, Kim's "reign of terror" continues and his nuclear weapons arsenal grows.

"It is time for the U.S. to counter this forgotten maniac," Gardner said.

"North Korea is a proliferator that has tested nuclear weapons on three separate occasions in violation of multiple U.N. Security Council resolutions. This past weekend it test-fired a ballistic missile from a submarine. That attempt failed, but Mr. Kim will try again," he added.

Pointing out the North's cyberwar capabilities, including last year's hacking attack on Sony Pictures, the senator said it would be "reckless to underestimate the regime's ability to damage American national or economic security through a cyberattack."

Gardner also said the North maintains a a network of political prison camps that hold as many as 200,000 people.

"The Obama administration's policy toward North Korea -- once described by then-Secretary of State Hillary Clinton as 'strategic patience' -- has been a strategic failure. We cannot stand by as the Kim regime builds its arsenal, intensifies its cyberespionage and tortures its own people," Gardner said.

"It is time to ratchet up the pressure," he added.

In October,  Gardner introduced a bill calling for imposing new sanctions on Pyongyang for its nuclear program, human rights abuses and cyber attacks. Co-sponsoring the legislation were presidential hopeful Marco Rubio and Sen. Jim Risch.

The bill would require the president to impose sanctions on people who have contributed to the North's nuclear program, enabled its human rights abuses, and engaged in money laundering, counterfeiting or drug trafficking that benefits the regime, the senator said.

"If the U.S. does not pursue increased sanctions, the threat will only grow. Now is the time to enact a strategy to quell North Korea's aggression -- to give our allies in the region a reason to trust us, and our enemies a reason to fear us," he said. (Yonhap)