A new rocket engine that North Korea claims to have successfully tested this week would be powerful enough to range the continental United States if it has the capability to put a satellite into orbit as claimed by Pyongyang, a top US commander said Tuesday.

The North claimed earlier Tuesday that it successfully conducted a "ground jet test of a new type high-power engine of a carrier rocket for the geo-stationary satellite." It said the "single engine" has a thrust of 80 tons, which is three times the power of the engine used in the North's previous long-range rocket launches.

The claim, if confirmed, would represent big progress in the North's efforts to develop an intercontinental ballistic missile capable of reaching the US The announcement also raises concern Pyongyang is preparing for yet another long-range rocket launch after a successful launch in February.

"There was news of a test of a new, very large rocket engine, a rocket engine that he (the North) said would be capable of going to the geosynchronous orbit in space. If it has that capability, it has the capability to reach the United States. So I'm very concerned about that," Air Force Gen. John E. Hyten said during a Senate hearing to confirm his nomination as commander of the US Strategic Command.

The State Department urged the North to stop such menacing actions that "destabilize the region and threaten international peace and security." It also urged Pyongyang to take concrete steps toward fulfilling its international obligations and commitments.

"We call on responsible stakeholders to join us in making clear to Pyongyang that further provocations are unacceptable and to consider what steps we can take together to raise the costs to Pyongyang of continuing to threaten us and the region," State Department spokesperson Katina Adams said.

The incoming strategic commander said the North is one of "the most likely threats and the most concerning."

"Russia is the most dangerous threat. China is a close second.

But the most likely threats and the most concerning are North Korea and then Iran, because North Korea is very unpredictable," Hyten said. "It's hard to tell exactly what they're going to do."

The commander also said the North will learn from failures and ultimately perfect its missile capabilities.

"When we started flying missiles and we started building those capabilities, we had failure after failure after failure and we ended up getting there. What concerns me most is they will get there. They're going to get there," Hyten said.

"Once they have those capabilities, what are they going to do with them? That's my biggest concern. If I'm confirmed as commander of STRATCOM, that will be at the top of my list to figure out how we best respond to that threat at hand," he said.

Hyten said one of his key focuses as strategic commander would be to "deter our adversaries and assure our allies that they are defended by the capabilities of the United States." He also said that the US should do more in terms of missile defense.

"I'm a big believer in missile defense. I think we're doing a lot, but I think we need to do more," he said. "I think the force is sized correctly today. I have some concerns about the size of that force in the future. (Yonhap)