North Korean leader Kim Jong Un has inspected a newly developed “ultramodern tactical weapon,” state media said Friday, without specifying what kind of weapon was tested.

North Korea has suspended nuclear and missile tests as it endeavors to improve relations with the outside world, and there was no indication that this weapon was nuclear-related or a missile. 

The State Department said it remains confident that promises made by Kim at his summit meeting with President Trump in Singapore in June would be fulfilled.

And in a positive sign, North Korea announced later Friday that it would deport a U.S. citizen who had been detained since October after being accused of entering the country illegally from China at the behest of the CIA.

However, the announcement about the new weapon test marked Kim’s first high-profile visit to a military site since the June summit, and the first announcement of any weapons test this year. 

It comes as Washington’s diplomatic efforts to persuade North Korea to give up its nuclear weapons program appear to have stalled.

Kim announced earlier this year that he is focused on economic rather than military development, and his inspection tours have reflected this, until now.

North Korean state media said that this week’s test, which took place at the Academy of National Defense Science, was successful and that Kim could not suppress his “passionate joy.”

“This result today is a justification of the party’s policy focused on defense science and technology, another display of our rapidly growing defense capabilities to the whole region and a groundbreaking change in strengthening our military’s combat capabilities,” Kim said.

Experts say North Korea has been growing increasingly frustrated with the United States over Washington’s insistence that sanctions would be lifted only at the end of a long process of denuclearization.

Earlier this month, North Korea’s Foreign Ministry warned that the country could return to the path of “pyongjin” — the simultaneous development of nuclear weapons and economic development — if sanctions are not lifted.

State media has also expressed anger in recent days over the resumption of small-scale joint military exercises by the United States and South Korea.

Friday’s announcement was not framed in those terms, as some missile tests have been in the past, but Shin Beom-chul, research fellow at the Asan Institute for Policy Studies, said it still “reads as a strategic move with deliberate political intention.”

It was an example of the North’s “coercive diplomacy,” he said.

“Pyongyang is putting pressure on Seoul and Washington for sanctions relief that they’ve been asking for,” he said. “Kim Jong Un is signaling that if such demand is not accommodated, Pyongyang can switch back to pursuit of nuclear development, as put forward in state media outlets recently.”

But Lee Jong-seok, a former South Korean unification minister now working at the Sejong Institute, a think tank, said Kim, as commander of his country’s armed forces, can carry out regular inspections of the country’s military facilities.

“That inspection does not necessarily read as deviation from any regular guidance activity that a country’s military commander would do,” he said. “The prime targets of ongoing disarmament talks are ICBMs and nuclear arms. Overreacting to activities outside that realm does not help achieve the ultimate end goal of denuclearization.”

Kim said the weapons system tested was one that especially interested his father, Kim Jong Il, who led its development personally before he died in office in 2011.

The State Department downplayed the news.

“We remain confident that the promises made by President Trump and Chairman Kim will be fulfilled,” a spokesman said in a statement late Thursday.

At their summit, Kim promised to work toward the denuclearization of the Korean Peninsula, while the two leaders also promised to open a new era of relations.

South Korea’s Unification Ministry said this week’s development was the first publicly known field inspection of a weapons test by Kim since he observed the testing of the Hwasong-15 intercontinental ballistic missile last November.