U.S. President Donald Trump said on Thursday he still has a good relationship with North Korean leader Kim Jong Un, with whom he held several summits during his first term, and referred to North Korea once again as a "nuclear power.

North Korea may soon seal its place in an exclusive global club after Kim Jong Un unveiled the country’s first nuclear-powered submarine under construction.

North Korea has conducted a slew of underwater-launched ballistic missile tests since 2016, all from the same 2,000-tonne submarine with a single launch tube. This particular submarine has been described by experts as a test platform rather than an operational submarine in active service.