Satellite images of a North Korean submarine facility show what appears to be a missile tube being developed for a future ballistic missile submarine.

The commercial imagery was disclosed Tuesday in an article published Tuesday by the group 38 North.

The photos show was appears to be a test stand for a submarine-launched ballistic missile.

"A review of commercial satellite imagery since 2010 covering submarine bases and submarine shipyards has identified a new test stand at the North’s Sinpo South Shipyard, probably intended to explore the possibility of launching ballistic missiles from submarines or of a shipboard vertical launch ballistic missile capability," wrote Joseph S. Bermudez Jr., a North Korea expert with AllSource Analysis, Inc.

The imagery obtained from DigitalGlobe, Inc. confirms a report first disclosed by the Free Beacon in August that North Korea was working to develop a submarine capable of launching ballistic missiles, potentially increasing the nuclear threat from the reclusive communist state.

U.S. intelligence agencies first reported the North Korean submarine missile development in internal reports last summer and the reports were later confirmed by South Korea’s military.

According to 38 North, "the new installation is the right size and design to be used for the research, development, and testing of the process of ejecting a missile out of a launch tube as well as evaluating its compatibility with submarines and surface combatants as well as the missiles themselves."

The report said a future North Korean missile-firing sub would give Pyongyang a survivable second-strike nuclear capability.

Meanwhile, the commander of U.S. forces in Korea said last week that he believes North Korea now has the capability to make a nuclear warhead for a missile.

Army Gen. Curtis Scaparratti, the commander, was asked by reporters about North Korea’s nuclear warhead capability and said the regime claims it already has miniaturized a weapon to fit on an intercontinental-range missile.

"Personally, I think that they certainly have had the expertise in the past," Scaparratti said. "They’ve had the right connections. And so I believe they have the capability to have miniaturized the device at this point, and they have the technology to potentially actually deliver what they say they have."

No nuclear warhead has been tested on a missile but "I don’t think as a commander we can afford the luxury of believing perhaps they haven’t gotten there," he said.

Scaparratti said North Korea remains dangerous and is continuing to develop both missile and nuclear weapons along with other asymmetric warfare means, such as special operations forces, submarines and cyber warfare capabilities.

The 38 North report said the potential threat of a North Korean submarine-launched nuclear missile should not be ignored or exaggerated.

It will likely take North Korea years to build a missile firing submarine.

The missile used could be a Musudan intermediate-range missiles, a Nodong medium-range missiles, or one of North Korea’s Russian-design short-range Scuds.

Additionally, North Korea could develop a vertical or torpedo-launched cruise missile for its submarines.

The submarine missile development also could assist Iran, which has a close relationship with North Korea on missiles and in the past has sent sailors to North Korea for submarine training.

The report said a search of commercial satellite imagery did not turn up photos of a missile-fire Russian-made Golf II-class submarine, the test stand was spotted at the east coast shipyard.

The SLBM development is likely being carried out by North Korea’s Maritime Research Institute, located near the Sinpo shipyard.

Photo analysis of the test stand indicates it appears to be the right size and design for ejection testing of a vertical missile launch tube used on submarines or surface ships "and possibly the initial stages of associated missile testing," the report said.

The submarine missile program is an outgrowth of earlier efforts to study firing missiles from merchant ships and is "just within the upper limit of current North Korean technological and industrial capability," Bermudez wrote.

The Free Beacon first reported Aug. 26 that U.S. intelligence agencies believe Pyongyang is building submarine-launched missiles that would increase the threat from the North’s missile arsenal.

North Korea has threatened to fire nuclear warheads against U.S. cities and has made videos depicting nuclear attacks on New York.

Military analysts said the missile-firing sub could be a modified Russian or Chinese design Romeo-class diesel submarines, or a copy of a Golf-class submarine purchased for scrap in the 1990s.

The current North Korean submarine force includes around 70 submarines, mostly aging diesel submarines, including 22 Romeo-class or Chinese Type-031s.

U.S. intelligence agencies also reported years ago that North Korea obtained submarine-launched ballistic missiles (SLBMs), specifically SS-N-6 SLBMs, from Russia. The SS-N-6 is the basis for North Korea’s new intermediate-range missiles.