North Korea “is on an aggressive schedule to build and deploy its first operational ballistic missile submarine,” said a Thursday memo on 38North, a project of the U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies.

Images taken on Nov. 5 show suspicious activity at North Korea’s Sinpo South Shipyard.

Strategists anticipated such a development after Pyongyang began testing submarine-launched ballistic missiles, or SLBMs, last year. Under dictator Kim Jong Un, the country’s nuclear weapons program has made great technological advances and signaled a willingness to use submarines for offensive military action.

According to the report, “The presence of what appear to be sections of a submarine’s pressure hull in the yards suggests construction of a new submarine, possibly the SINPO-C ballistic missile submarine – the follow-on to the current SINPO-class experimental ballistic missile submarine.”

Throughout 2017, there has been a continued movement of parts and components in and out of two parts yards adjacent to the constructions halls in the center of the shipyard, the report said.

Commercial satellite imagery taken on in early November showed two large circular objects that could be sections of a submarine’s pressure hull in a shipyard located within the North Korean port city of Sinpo. The report noted that these appeared larger than those for North Korea’s ROMEO-class attack submarine.

Images of a test stand indicated continued testing of a mechanism to facilitate the ejection launch of missiles from a submarine.

Analysis completed in October by the Defense Intelligence Agency revealed that North Korea had successfully produced a miniaturized nuclear warhead that can fit inside its missiles, which means that the rogue regime is well on its way to becoming a full-fledged nuclear power.

However, the report said no activity could be seen, suggesting preparations for a new test of a submarine-launched missile.

North Korea is also thought to be working on a solid-fuel missile for submarine launches.

Last month, The Diplomat magazine quoted a U.S. government source as saying U.S. military intelligence had detected a new diesel-electric submarine under construction at Sinpo and dubbed it the Sinpo-C. It noted that the submarine was likely a larger successor to North Korea’s single experimental ballistic missile submarine.

North Korea has conducted dozens of missiles tests this year; its biggest nuclear test being on Sep. 3. The country has not tested a missile since firing one over Japan on Sep. 15.

Trump has put his foot down when it comes to any foreign nation or entity doing business with North Korea. “Do business with North Korea, and you won’t be doing business with the U.S.,” Trump declared more than one month ago.

In a tweet last Thursday Trump wrote, “China is sending an Envoy and Delegation to North Korea – A big move, we’ll see what happens!”