North Korea's recent military threats are worrisome especially as the "stability" of North Korea's young leader Kim Jong-un remains uncertain, a senior U.S. lawmaker said Sunday.

Rep. Mike Rogers, the chairman of the House Intelligence Committee, said North Korea has the capability to carry out its verbal threats.

"They certainly have a ballistic missile that can reach U.S. shores," he said, appearing on a CNN program.

The Michigan republican did not specify whether he meant the U.S. mainland or closer regions like Hawaii or Alaska.

"So, you have a 28-year-old leader who is trying to prove himself to the military and the military eager to have a saber rattling for their own self-interest and the combination of that is proving to be very deadly," he said.

He cited Pyongyang's threats to launch a nuclear strike against the U.S. "This is very, very concerning as we just don't know the stability of their leader," he added.

North Korea is known for its erratic acts. Furthermore, many U.S. officials say it's more difficult to fathom the current leader's strategy than that of his late father Kim Jong-il.

Last week, James Clapper, the head of the U.S. intelligence community, told the Senate that the North's ruler is so belligerent that his regime could take provocative actions against the U.S. or South Korea.

Sen. Bob Corker (R-TN), however, said for now North Korea does not appear to have long-range missile capability to hit the U.S. mainland despite its one-time success of putting a satellite into orbit.

"I don't think they have the delivery mechanisms that are necessary to really harm us," said the ranking member of the Senate Foreign Relations Committee.

He stressed the need to take "precautionary measures" to stay ahead of Pyongyang's threats.

He lauded the Pentagon's decision to bolster its missile defense system.

On Friday, Secretary of Defense Chuck Hagel announced plans to deploy 14 additional ground-based interceptor missiles in Alaska by 2017 and set up another radar station in Japan.

It would increase the number of U.S. ground-based interceptors (GBIs) in Alaska to 44.

Hagel made it clear that the move is aimed at better protecting his homeland from North Korean threats.

Speaking to reporters, Adm. James Winnefeld, the vice chairman of the Joint Chiefs of Staff, also admitted that Pyongyang's missile development "went just a little bit faster" that the U.S. might have expected.

Although the North's road-mobile intercontinental ballistic missile, known as the KN-08, has not been tested yet, he noted, it is believed to have the range to reach the U.S. mainland. (Yonhap News)