WASHINGTON — President Joe Biden reiterated U.S. commitment to the Philippines’ security and noted the “deep friendship” of the two nations as he hosted Philippines President Ferdinand Marcos Jr. for White House talks Monday as concerns grow about the Chinese navy’s harassment of Philippine vessels in the South China Sea.

Marcos’ visit to Washington comes after the U.S. and the Philippines last week completed their largest war drills ever and as the two countries’ air forces on Monday will hold their first joint fighter jet training in the Philippines since 1990. The Philippines this year agreed to give the U.S. access to four more bases on the islands as the U.S. looks to deter China’s increasingly aggressive actions toward Taiwan and in the disputed South China Sea.

Meanwhile, China has angered the Philippines by repeatedly harassing its navy and coast guard patrols and chasing away fishermen in waters that are close to Philippine shores but that Beijing claims as its own.

But as Biden sat down with Marcos, the U.S. president went out of his way to note the progress in the U.S.-Philippine relationship—one that has had ups and downs over the years and was in a difficult place when Marcos took office less than a year ago.

“We are facing new challenges and I couldn’t think of a better partner to have than you.” Biden told Marcos at the start of their Oval Office meeting. “The United States also remains ironclad in our commitment to the defense of the Philippines, including in the South China Sea, and we will continue to support the Philippines military modernization.”

Marcos said the relationship was essential as Philippines and the Pacific finds itself in “possibly the most complicated geopolitical situation in the world right now.”