North Korea’s Nuclear Program Advancing, U.S. Military Leader Says

North Korea now has the capability to manufacture a nuclear warhead that can be placed on a rocket, a significant step forward in Kim Jong Un’s efforts to develop nuclear missiles, a top U.S. commander told reporters on Friday.

For years, North Korea has struggled to make strides in its nuclear program. Gen. Curtis Scaparrotti, commander of U.S. forces on the Korean peninsula, said that’s changed: North Korea can build a miniaturized nuclear warhead, a precursor to a nuclear missile.

"I believe they have the capability to miniaturize a device at this point, and they have the technology to actually deliver what they say they have," Scaparrotti said. He hedged his comments by adding that they were his opinions, not facts. But he said that North Korea’s relationship with other nuclear powers led him to believe that North Korea has made strides.

"They have proliferation relationships with other countries, Iran and Pakistan in particular," Scaparrotti said.

Scaparrotti’s comment came as tensions between North and South Korea are on the rise. There have been a number of small skirmishes along the demilitarized zone, initiated by North Korean troops.

"We sternly warn North Korea against reckless military provocations … that would raise military tensions," South Korean Defense Ministry spokesman Kim Min-seok said earlier this week.

The new warning about North Korean nuclear advances also follows a delay in the return of wartime control of the South Korean military back to Seoul from Washington. The deal, which serves as a deterrent to Pyongyang, was set to expire next year.

In a joint statement announcing the delay, South Korea and the United States said on Thursday that extra time would allow Seoul to "focus on South Korea achieving critical defensive capabilities against an intensifying North Korean threat."