U.S. President Barack Obama delivers remarks after touring the Philippine Navy's BRP Gregorio Del Pilar, a former U.S. vessel, at Manila Harbor, Nov. 17, 2015. Obama said the U.S. will give the Philippines two more ships to help defend its borders. Reuters

President Barack Obama said Tuesday the U.S. would give the Philippines two more ships that will aid the Southeast Asian nation in defending its claims in the South China Sea against China expansionism. Obama is in Manila for the Asia-Pacific Economic Cooperation (APEC) summit, which Chinese President Xi Jinping is also attending.

"We have a treaty obligation, an ironclad commitment to the defense of our ally, the Philippines," the Associated Press quoted Obama as saying, standing before a frigate the Philippines got from the U.S. in 2011. "You can count on the United States. My visit here underscores our shared commitment to the security of the waters of this region and to the freedom of navigation."

The two additional ships are a coast guard cutter and a research vessel. The frigate, BRP Gregorio del Pilar, was already in a standoff with Chinese forces in 2012, when Philippine soldiers tried to arrest Chinese fishermen in a disputed area.

In the past year, China has exercised its claim to owning most of the South China Sea by building artificial islands with airstrips and other facilities in areas claimed by the Philippines. In June, it also brought back an oil rig to an area claimed by Vietnam, after withdrawing it for a year.

Philippine President Benigno Aquino has been the loudest voice against China's moves. China's failure to invite him to the China-ASEAN Expo in Nanning in 2013 has been traced to this. ASEAN is the Association of Southeast Asian Nations. But Aquino was in Beijing for APEC last year.

Last year, the Philippines took China to the Permanent Court of Arbitration in the Netherlands. China said the court has no jurisdiction but last month the court said it did, paving the way for a trial.

That was just days after the U.S. sent a Navy ship close to one of those islands, within the 12-mile radius China claims, and then B-52 bombers. It said it would send ships as often as twice per quarter as part of what it calls its freedom of navigation program.

Obama is scheduled to meet Australian Prime Minister Malcolm Turnbull later Tuesday. The fight against the Islamic State group, also known as ISIS, was on their agenda even before the attacks in Paris last week.

On Wednesday, Obama has meetings with Aquino and the leaders of 11 other economies that signed the Trans-Pacific Partnership agreement last month. China is not part of that agreement. Obama will attend the APEC events on Thursday, before flying to Kuala Lumpur on Friday for the ASEAN and East Asia summits.