President Moon Jae-in reiterated calls for a formal end to the 1950-53 Korean War at the United Nations General Assembly on Tuesday, amid fresh tension on the Korean Peninsula following recent ballistic missile tests by both Koreas.

“I once again urge the community of nations to mobilize its strengths for the end-of-war declaration on the Korean Peninsula,” Moon said as he addressed the annual gathering of world leaders in New York. “I propose that three parties of the two Koreas and the US, or four parties of the two Koreas, the US and China come together and declare that the war on the Korean Peninsula is over.”

He added that it would be possible to achieve “irreversible progress in denuclearization and usher in an era of complete peace” when the parties involved in the Korean War together proclaimed an end to the war.

The two Koreas are technically still at war, as the Korean War ended not in a peace treaty but in an armistice agreement signed by the US-led United Nations Command, China and North Korea.

Moon has called strongly for an end-of-war declaration throughout his presidency, arguing that such a declaration could encourage Pyongyang to give up its nuclear weapons. But the US has said the North first needs to take concrete steps toward denuclearization.

During the historic summit in the border village of Panmunjom in 2018, the leaders of the two Koreas agreed to cease all hostile acts and work toward formally ending the war, but no such declaration has materialized since the collapse of US-North Korea talks in 2019.

The UN address marked Moon’s last speech at the annual session, with his single five-year term due to end in May. He made similar pleas to replace the armistice with a peace treaty during his UN speech in 2018 and again last year.

Tensions are running high between the two Koreas amid a heated arms race. Last Wednesday the North fired two ballistic missiles into the East Sea, defying a UN ban, just days after testing a new long-range cruise missile. On the same day South Korea tested its first submarine-launched ballistic missile.

While Seoul said the test was preplanned and not a direct response to the North’s launches, Moon has said the South’s growing missile capabilities will serve as “sure deterrence” against Pyongyang’s provocations.

At the UN Moon made no mention of missiles, but called for reconciliation and unification while stressing that this year marks the 30th anniversary of the two Koreas being admitted to the UN.

“With the joint accession to the UN, the two Koreas both recognized that they were two separate nations different in systems and ideologies,” he said. “However, such was never meant to perpetuate the division. For when we acknowledged and respected each other, only then could we set out on a path to exchange, reconciliation and unification.”

Moon also called for the “speedy resumption” of dialogue between the two Koreas and between the US and North Korea.

“I hope to see that the Korean Peninsula will prove the power of dialogue and cooperation in fostering peace.”

The president also urged Pyongyang to “brace for changes that benefit the era of global community.”

“I expect that the international community, together with Korea, remain always ready and willing to reach out to North Korea in a cooperative spirit,” he said.

Denuclearization talks between Pyongyang and Washington have been stalled since the collapse of the Hanoi summit in 2019, when former US President Donald Trump rejected Kim Jong-un’s offer of denuclearization in exchange for sanctions relief. Since then, inter-Korean ties have also remained at a standstill.

Meanwhile, at the UN gathering US President Joe Biden highlighted diplomacy as a means to completely denuclearize the Korean Peninsula.

“Similarly, we seek serious and sustained diplomacy to pursue the complete denuclearization of the Korean Peninsula,” Biden said in his first speech to the UN as president.

“We seek concrete progress toward an available plan with tangible commitments that would increase stability on the peninsula and in the region, as well as improve the lives of the people in the Democratic People’s Republic of Korea,” he said, referring to the North by its official name.

The US has repeatedly called for dialogue with the North, with Biden’s point man on North Korea, Sung Kim, saying he was willing to meet his North Korean counterparts “anywhere, anytime, without preconditions.”

But the North has remained largely unresponsive, saying it will not return to talks until the US drops its “hostile” policy toward Pyongyang, an apparent reference to US-led sanctions.