North Korean leader Kim Jong Un has overseen the successful tests of two types of tactical ballistic missiles, including one with a “super-large conventional warhead” and an “improved” cruise missile, according to North Korean state media.

The tests were a response to the “grave threat” posed by outside forces to North Korea’s security, state-run KCNA reported Kim as saying on Thursday.

The tests involved Hwasongpho-11-Da-4.5 missiles, mounted with a 4.5-tonne super-large conventional warhead, KCNA said. North Korea previously announced tests for that weapon in July.

Kim stressed “the need to continue to bolster up the nuclear force and have the strongest military technical capability and overwhelming offensive capability in the field of conventional weapons too”.

South Korea’s military and a number of political analysts have suggested North Korea is testing weapons with a view to exporting them to Russia.

Pyongyang, which is under major international sanctions over its weapons programme, has denied the trade with Russia but has bolstered military ties with Moscow.

Kim met President Vladimir Putin in Russia’s east last year, while Putin visited Pyongyang in June, with the two leaders signing a mutual defence agreement.

Russian security chief Sergei Shoigu was also in Pyongyang last week.

Photos released by KCNA showed Kim watching the latest tests as well as a missile hitting a ground target. South Korea’s military said later on Thursday that it had assessed that the ballistic and cruise missiles fired by North Korea the previous day had come down in North Korea’s mountainous northeastern region.

North Korea typically tests missiles off its east coast, with the missiles landing in the sea.