North Korea may deploy additional troops to Russia to fight in the war against Ukraine in July or August and Pyongyang is continuing supplying arms to Russia, South Korea's lawmakers said on Thursday, citing a briefing by the intelligence agency.

North Korea did not officially confirm until late April that it had sent more than 10,000 troops and weapons to Russia as the countries' military ties grew dramatically under a comprehensive strategic partnership treaty signed by Kim and Russian President Vladimir Putin last year.

Kim Jong Un has said his country's involvement in the Russia-Ukraine war was justified, calling it an exercise of sovereign rights in defense of a “brother nation,” state media KCNA reported on Saturday.

"Our participation in the conflict was just, and it falls within the sovereign rights of our Republic,"Kim said, according to KCNA. "I consider all the brave soldiers who participated in the Kursk operation to be heroes and the highest representatives of the nation’s honor," he added.