Secretary of State Mike Pompeo’s visit to North Korean capital Pyongyang did not go well this week as the Foreign Ministry for the authoritarian regime says the talks were “regrettable,” signaling a bump in the road as negotiations for the removal of the country’s nuclear weapons program stall. North Korean officials have released a statement according to CNBC explaining that the U.S. is making unwarranted unilateral demands for denuclearization.

The commentary comes after two days of discussion between Pompeo and a delegation of North Korean officials led by General Kim Yong Chol, the country’s former head of espionage.

North Korea claims the U.S. has abandoned the original “spirit” of last month’s meeting in Singapore between President Donald Trump and leader Kim Jong-Un, slamming the unilateral demands on the “complete, verifiable, and irreversible denuclearization” (CVID) of the North.

The statement explains the outcome of the follow-up talks with Pompeo were “very concerning” since it will ultimately led to a, “dangerous phase that might rattle our willingness for denuclearization that had been firm.”

Although Kim made promises to Trump about the scaling down of nuclear operations while meeting in Singapore, North Korea is still moving forward with its missile capabilities and strengthening its military might. Newsweek reports the North is continuing construction on a new submarine capable of carrying three ballistic missiles, according to military reports from South Korean lawmaker Kim Hack-yong.

The submarine program would proliferate the North’s military reach around the world as their intercontinental ballistic missiles could reach further than before.¬†The regime’s submarine-launched missile program was first made public in 2014. Four to six test launches have been undertaken since then, with a test firing in 2016 traveling over 300 miles, signaling the program’s progression.

“Contrary to our military’s suspension of joint Korea-U.S. military exercises, North Korea is conducting military exercises on a scale similar to previous years,” Kim said, reinforcing the notion that South Korea should continue to strengthen its “military preparedness” as negotiations continue.

There is another meeting scheduled between the U.S. and North Korea on July at the Demilitarized Zone (DMZ), with the Department of Defense taking the lead. However, with tension rising after last week’s meeting its fate is unclear.