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While Donald Trump has been busy playing up his — and his wife’s — special relationship with Kim Jong Un, the North Korean dictator has been busy expanding his weapons program.

A new report suggests that North Korea is building a submarine capable of launching nuclear missiles. Satellite imagery taken on Monday and published by Beyond Parallel, a research project funded by the Center for Strategic and International Studies (CSIS), suggests circumstantial evidence of the construction of a new ballistic missile submarine at the Sinpo South Shipyard.

The researchers, Joseph Bermudez and Victor Cha, add that “preliminary evidence indicates possible preparations for a test,” though they added that even after construction is complete it would take at least a year for the submarine to become fully operational.

The researchers describe the ballistic missile submarine threat as “emerging rather than imminent.”

Last month, North Korea’s state news agency reported that Kim had inspected a new submarine at an unspecified location. Kim said the submarine was “an important component in the national defense of our country”

Separately, Japan claimed Tuesday that North Korea is testing missiles that feature new warheads capable of breaching Japan’s missile defense systems.

Defense Minister Takeshi Iwaya told a news conference that Tokyo believes the rockets Pyongyang is testing are new short-range ballistic missiles. To back up his claim that the new missiles could breach Japan’s missile defense system, he pointed to the irregular trajectories observed during the recent tests.

North Korea has launched eight short-range missiles in the last five weeks, the most recent on Saturday. When asked about the tests during the G7 meeting of world leaders in France on Sunday, Trump played down their significance, telling reporters that lots of countries are testing such missiles.

“We are in a world of missiles folks, whether you like it or not,” Trump said.

Trump said that Kim had agreed at their first summit in Singapore in June 2018 not to test any more long-range ballistic missiles, and he had kept that agreement.

But the U.S. and North Korea have been at loggerheads since Trump walked out of a second round talks with Kim in Hanoi in February. Washington is seeking total denuclearization before lifting sanctions, while Pyongyang wants sanctions relief before it denuclearizes.

The new evidence suggesting North Korea is developing a submarine capable of launching a nuclear missile is only likely to harden Washington’s position.

“The construction and commissioning of a true [ballistic missile submarine] capability would represent a significant advancement of the North Korean ballistic missile and nuclear threat and complicate defense planning in the region, given the difficulties of tracking and/or pre-emptively targeting such capabilities,” Bermudez and Cha say in their report.

“The images suggest North Korea is making real progress in developing a second leg of the nuclear triad, bringing them closer to a survivable nuclear force,” the analysts add.

Secretary of State Mike Pompeo told veterans on Tuesday that he hoped talks on denuclearization would recommence soon. But with North Korean Foreign Minister Ri Yong Ho last week calling Pompeo “the diehard toxin of the U.S. diplomacy," there is unlikely to be any breakthrough in the short-term.