Unless it is stopped, North Korea will eventually acquire intercontinental ballistic missile capabilities, the four-star general selected to lead US forces in South Korea told lawmakers Tuesday.

Speaking at his nomination hearing before the Senate Armed Services Committee, General Vincent Brooks warned that North Korean leader Kim Jong-Un was determined to build rockets that could one day reach as far as the United States.

"It's very clear through the parades that they've done, what systems they have and some of the attempted launches that ... over time, I believe we're going to see them acquire these capabilities if they're not stopped," Brooks said.

Senator John McCain, who chairs the committee, asked Brooks how concerned he was about the "immaturity and unpredictability of the rotund ruler in Pyongyang."

"I'm very concerned about the direction he's going, and it's evident that he's not yet deterred from his pursuit," Brooks responded.

"If confirmed, I intend to be a close partner with the Republic of Korea to make sure they're ready."

The US military has kept a huge contingent of troops in South Korea since the end of the Korean War in 1953.

The two Koreas technically remain at war, because the conflict ended in an armistice instead of a peace treaty.

Currently, about 28,500 US troops are stationed in South Korea, and the two forces have very close military ties and continually conduct joint training.

Brooks also voiced concern about North Korea's pursuit of building submarine-launched ballistic missiles.

"While they have not been successful, this is like watching someone ride a bike and falling off of it, but eventually they could become a BMX champion," he said.

The Pentagon is confident it has adequate missile defenses to protect against a threat from North Korea, but officials have watched with increasing alarm as Kim pushes forward with his nuclear tests and missile program.

Pyongyang last week conducted a test of what appeared to be a medium-range missile, but the rocket suffered a catastrophic failure on launch.

Washington and Seoul are discussing the deployment to South Korea of a sophisticated THAAD system -- Theater High Altitude Area Defense System -- to protect against ballistic missiles from the North.

McCain indicated that the committee would move forward with Brooks's nomination.