WASHINGTON -- President Joe Biden reiterated U.S. commitment to the Philippines' security and noted the 鈥渄eep friendship鈥 of the two nations as he welcomed 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鈥檚 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鈥攐ne that has had ups and downs over the years and was in a difficult place when Marcos took office less than a year ago.

鈥淲e are facing new challenges and I couldn鈥檛 think of a better partner to have than you.鈥 Biden told Marcos at the start of their Oval Office meeting. 鈥淭he 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.鈥

Marcos said the relationship was essential as Philippines and the Pacific finds itself in 鈥減ossibly the most complicated geopolitical situation in the world right now.鈥

Monday's Oval Office meeting is the latest high-level diplomacy with Pacific leaders by Biden as his administration contends with increased military and economic assertiveness by China and worries about North Korea's nuclear program. Marcos鈥 official visit to Washington is the first by a Philippine president in more than 10 years.

The U.S. president last week hosted South Korean President Yoon Suk Yeol for a state visit during which the two leaders introduced new steps aimed at deterring North Korea from launching an attack on its neighbours. Biden is scheduled to travel to Japan and Australia in May.

The two sides are expected to discuss the security situation and come out with new economic, education, climate and other initiatives as part of Marcos鈥 four-day visit to Washington, according to two senior Biden administration officials.

The officials, who briefed reporters on the condition of anonymity to preview the leaders' meeting, said the White House will use the visit to announce the transfer of three C-130 aircraft and coastal patrol vessels to the Philippines, a new U.S. trade mission focused on increasing American investment in the Philippines' innovation economy, new educational programming and more.

Increased Chinese harassment of vessels in the South China Sea has added another dimension to the visit. On April 23, journalists from The Associated Press and other outlets were aboard the Philippine coast guard鈥檚 BRP Malapascua near Second Thomas Shoal when a Chinese coast guard ship blocked the Philippine patrol vessel steaming into the disputed shoal. The Philippines has filed more than 200 diplomatic protests against China since last year, at least 77 since Marcos took office in June.

State Department spokesperson Matthew Miller on Saturday called media reporting on the encounters a 鈥渟tark reminder鈥 of Chinese 鈥渉arassment and intimidation of Philippine vessels as they undertake routine patrols within their exclusive economic zone."

"We call upon Beijing to desist from its provocative and unsafe conduct,鈥 Miller said.

U.S. and Taiwanese officials have also been unnerved by recent critical comments by China鈥檚 ambassador to the Philippines, Huang Xilian, over the Philippines granting the U.S. military increased access to bases.

Huang at an April forum reportedly said the Philippines should oppose Taiwan's independence 鈥渋f you care genuinely about the 150,000 OFWs鈥 in Taiwan, using the acronym for overseas Filipino workers.

China claims the self-ruled island as its own. The Philippines, like the U.S., has a 鈥淥ne China鈥 policy that recognizes Beijing as the government of China but allows informal relations with Taiwan. Marcos has not explicitly said that his country would assist the United States in any armed contingency in Taiwan.

The officials described Huang鈥檚 comments as one of many recent provocative actions by the Chinese to put pressure on the Philippines.

One official said that Marcos still desires to work closely with both Washington and Beijing but that he 鈥渇inds himself in a situation鈥 in which 鈥渢he steps that China is taking are deeply concerning.鈥

Close U.S.-Philippines relations were not a given when Marcos took office. The son and namesake of the late Philippines strongman had seemed intent on following the path of his predecessor, Rodrigo Duterte, who pursued closer ties with China.

Before Marcos took office last year, Kurt Campbell, coordinator for Indo-Pacific affairs on the White House National Security Council, acknowledged that 鈥渉istorical considerations鈥 could present 鈥渃hallenges鈥 to the relationship with Marcos Jr. It was an oblique reference to long-standing litigation in the United States against the estate of his father, Ferdinand Marcos.

A U.S. appeals court in 1996 upheld damages of about US$2 billion against the elder Marcos鈥 estate for the torture and killings of thousands of Filipinos. The court upheld a 1994 verdict of a jury in Hawaii, where he fled after being forced from power in 1986. He died there in 1989.

Marcos noted that he last visited the White House when his father was in power.

Biden and Marcos met in September during the UN General Assembly, where the U.S. president acknowledged the two countries' sometimes 鈥渞ocky鈥 past.

During their private meeting, Biden, a Democrat, stressed to Marcos his desire to improve relations and asked Marcos how the administration could 鈥渇ulfill your dreams and hopes" to do that, a senior administration official told the Associated Press.

Marcos is also slated to visit the Pentagon, meet Cabinet members and business leaders and make remarks at a Washington think tank during his visit.

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Gomez reported from Manila. AP writer Colleen Long contributed reporting.