MANILA -- The front-runner in the 2016 Philippine presidential campaign has backed the government’s move to take China to court in a dispute over the South China Sea, increasing the likelihood that the island nation will continue to challenge China alongside U.S. efforts to keep the sea lanes there open. “We should be able to pursue cooperation, equity and amity with other nations, China included,” Philippine Sen. Grace Poe said in a televised forum. “But together with that we should strengthen our military, our coast guard, and maintain that support."

Poe said the Philippines should continue arbitration with China under the United Nations Convention on the Law of the Sea, but should also engage other members of the Association of Southeast Nations (ASEAN) "for a constructive dialogue and to see how we can uphold the rule of law especially with regard to our territorial waters.”

The Permanent Court of Arbitration in the Netherlands on Tuesday began hearing the Philippines’ case against China, which it initiated in January 2013. China has denied the court’s jurisdiction and refused to participate.

Philippine President Benigno Aquino III has accused China of encroaching on its territory. While China has long claimed most of the sea, it has become more assertive in the past year, using reclamation to create or expand islands on which it is building airstrips and other facilities.

In October, the U.S. reacted by sending the guided missile destroyer USS Lassen within the 12-mile radius China claims around one of those islands, despite China’s warnings not to. The U.S. says it will send two such missions every quarter. This month, Defense Secretary Ash Carter helicoptered to the carrier USS Theodore Roosevelt as it plied the sea, stating there that it was China causing the tensions in the area.

Then last week in Manila for the Asia-Pacific Economic Cooperation summit, President Barack Obama called on China to stop reclamation and said the U.S. was giving the Philippines two more decommissioned ships to add to its small navy. Aquino made similar statements in Kuala Lumpur, Malaysia, last weekend, during the ASEAN and East Asia summits.

Poe is leading the presidential race with 39 percent support, according to an October survey. The election is scheduled for May 9.

Poe's main challengers are Vice President Jojo Binay and Aquino’s candidate, former Secretary of the Interior and Local Government Mar Roxas, both at around 20 percent. Roxas and Binay -- who participated in a separate forum hours before -- weren’t asked and didn’t speak about China even though it’s been increasingly in the news.

All three spoke about lifting foreign ownership restrictions, which is needed for the Philippines to join the U.S.-led Trans-Pacific Partnership and which some say is needed to boost investments and jobs.

Poe and Binay said they were for relaxing the restrictions in the constitution. Roxas said the Philippines has to be careful about joining TPP, not because of its investment rules but because of some of its trade provisions.

“There are other reasons we have to be careful about joining TPP,” Roxas said. “In agriculture,  they have subsidies for their farmers. Our farmers cannot compete. You will wipe out a sector comprising one-third of our population if you just mindlessly enter TPP without support for our agricultural sector.”

He also said relaxing foreign ownership restrictions won’t boost investment if investors still have to deal with red tape and corruption.

“While that possibility exists, that’s not where I am going to focus,” Roxas said. “I’m going to focus on making sure that ‘ease of doing business’ is not just some words that are up there but really become easier to do business.

“That’s not what’s our stumbling block. We need to pay attention to our real problems and not go off chasing some magic wand that by simply changing the constitution our economy will grow.”