North Korean leader Kim Jong Un has inspected a newly built submarine and ordered officials to further bolster the country’s military capabilities, state media reported Tuesday.

It comes as the North increases pressure on the United States ahead of the possible resumption of nuclear diplomacy.

Last week, North Korea said it may lift its 20-month suspension of nuclear and missile tests in protest against expected military drills between the United States and South Korea that Pyongyang says are an invasion rehearsal.

The submarine report comes as the US and North Korea work to resume talks agreed to after a meeting late last month on the Korean border between Mr Kim and US President Donald Trump.

Diplomacy has been stalled since the second Kim-Trump summit in Vietnam in February fell apart due to differences over US-led sanctions on North Korea.

Kim Jong Un, left, inspects a newly built submarine
Kim Jong Un, left, reportedly inspects a newly built submarine (Korean Central News Agency/Korea News Service via AP)

The North’s official Korean Central News Agency reported that Mr Kim expressed “great satisfaction” with the submarine after learning about its operational and tactical data and weapon systems.

He “stressed the need to steadily and reliably increase the national defence capability by directing big efforts to the development of the naval weapons and equipment such as submarine”, according to KCNA.

KCNA did not say exactly when or where Mr Kim’s inspection of the submarine took place. It said the submarine’s operational deployment “is near at hand”.

The construction of a new submarine suggests North Korea has been increasing its military capability despite nuclear diplomacy with the US that began early last year.

North Korea has repeatedly said it is willing to abandon its nuclear programme in return for political and economic benefits.

But there has been little public progress despite the most recent Trump-Kim meeting, and the North’s release of the submarine photos could be a way to both increase pressure on the United States ahead of any renewed talks and remind its rival of its demands.

North Korea wants widespread relief from harsh US-led sanctions in return for pledging to give up parts of its weapons programme, but the United States is demanding greater steps toward disarmament before it agrees to relinquish the leverage provided by the sanctions.

It was not known exactly what kind of submarine North Korea has built. But its efforts to develop submarine-launched missile systems are a serious concern for rivals and neighbours because missiles from submerged vessels are harder to detect in advance.

Before it entered talks with the United States, North Korea claimed to have successfully test-fired ballistic missiles from submarines, though many outside analysts say the country remains years away from having an operational system.

According to a South Korean defence report in 2018, North Korea has 70 submarines and submersibles.