South Korean President Yoon Suk-yeol and Philippine President Ferdinand Marcos Jr. agreed on Monday to boost defense cooperation as their countries elevated ties to a strategic partnership amid growing security challenges in the region.

The two leaders discussed a range of issues including tensions in the South China Sea and on the Korean Peninsula during talks at the Philippine presidential palace, where they also signed agreements on coastguard cooperation and nuclear energy.

"President Marcos and I opened a new chapter of our partnership by elevating our relationship to a strategic partnership," said Yoon, who is on a state visit to Manila, the first by a South Korean leader in more than a decade.