Japan's Prime Minister Shinzo Abe has won support for his plans to boost his country's military from the visiting leader of the Philippines, which suffered greatly under wartime occupation by the Japanese army.

Philippine President Benigno Aquino voiced his backing on Tuesday for Abe's push to reinterpret Japan's pacifist Constitution.

This would allow the Japanese military to defend not only Japan but also allies that come under attack or any country that Japan identifies as being vital to its self-defense.

Japan has committed to providing the Philippines with 10 patrol vessels, Gilberto Asuque, charge d'affaires at the Philippine embassy in Tokyo, said on Monday.

Experts warned that Tokyo and Manila are militarizing maritime problems related to China and said the Philippines is making a dangerous political trade at the expense of regional stability.

The Philippines was occupied by Japan from 1942 to 1945, and Manila was reduced to rubble.

But on Tuesday, Aquino welcomed a greater role for the Japanese military and endorsed the concept of "collective self-defense", whereby Japan can give military aid to other countries.

"We believe that nations of goodwill can only benefit if the Japanese government is empowered to assist others," Aquino said at a joint news conference with Abe following a summit in Tokyo.

China has criticized Japan's push for collective self-defense, warning against the return of the Japanese militarism that wreaked havoc across much of Asia before and during World War II.

Li Jinming, a professor of maritime law and South China Sea studies at Xiamen University, said Aquino is seeking powerful support by fair means or foul to boost claims to islands and is ignoring the past. "Japan is also trying to muddy the waters of the South China Sea, and Tokyo's military aid is clearly some sort of military expansion and buildup."

The Associated Press reported that neither Aquino nor Abe mentioned China by name, "but both referred to the changing security environment".

Abe said they also discussed the transfer of defense equipment.

Yang Bojiang, an expert on Japanese studies at the Chinese Academy of Social Sciences, said Tokyo and Manila's language comes across as "repeated cliches", but the "transfer of military equipment" from Japan warrants scrutiny.

Japan is selling defense products to Southeast Asian nations, courting the Philippines for stronger military muscle to challenge China, Yang added.