President Volodymyr Zelenskyy said Tuesday he had agreed with South Korea's president to step up contacts between their nations at all levels to develop countermeasures and a strategy to respond to North Korea's involvement in the war in Ukraine.

Zelenskyy, in a readout of a phone call with President Yoon Suk Yeol published on X, said the two leaders also agreed to strengthen exchanges of intelligence and expertise.

"As part of this agreement, Ukraine and the Republic of Korea will soon exchange delegations to coordinate actions," he said.

Zelenskyy said he shared data about the deployment of 3,000 North Korean troops to Russian training grounds near the combat zone, with their presence expected to increase to approximately 12,000.

"We agreed to strengthen intelligence and expertise exchange, intensify contacts at all levels, especially the highest, in order to develop an action strategy and countermeasures to address this escalation, and to engage our mutual partners in cooperation," he said.