Philippine President Benigno Aquino made a veiled comparison on Wednesday between China's activities in the South China Sea and Nazi Germany's expansionism before World War Two, echoing similar remarks he made last year that outraged Beijing.
Aquino, who is expected to agree to beefed up defence ties with Japan when he meets Prime Minister Shinzo Abe on Thursday, also urged Beijing to rethink its land reclamation projects in the disputed waters.
China has been taking an increasingly assertive posture in recent years in the South China Sea, building artificial islands in areas where Manila and other Southeast Asian countries have rival claims.
Asked about Washington's strategic "rebalance" to Asia and China's maritime moves, Aquino suggested the US' role was key, and alluded to Nazi Germany's territorial expansion before World War Two and Western appeasement.
"If there was a vacuum, if the United States, which is the superpower, says 'We are not interested', perhaps there is no brake to ambitions of other countries," he said at an event sponsored by the Nikkei business newspaper.
Recalling a documentary on Germany's expansionism before the war, Aquino added: "The commentators on this documentary were saying, 'If somebody said stop to (Adolf) Hitler at that point in time, or to Germany at that time, would we have avoided World War Two?'"
Aquino made similar comments last year, which China branded "outrageous and totally unreasonable".
The Philippine leader also said Beijing's South China Sea land reclamation projects appeared to violate an international agreement.
China and the 10-member Association of South East Asian Nations (ASEAN) signed an agreement in 2002 to refrain from occupying uninhabited reefs and shoals in the sea, and from building new structures that would complicate disputes.
"Perhaps they should re-examine all of these efforts and see whether or not this is necessary given the increasing tensions."
During Aquino's state visit, Tokyo and Manila are likely to agree to start talks on a framework for the transfer of defence equipment and technology, the latest move by Abe to beef up ties with Asian nations facing China's naval ambitions.
Japan, which last year eased restrictions on arms exports, already has such agreements with the United States, Britain, Australia and France.
In comments echoed later in a speech to parliament, Aquino noted how Japan and the Philippines had overcome their wartime past to become close partners.
"Japan has been steadfast in demonstrating its solidarity with the Philippines as we advocate freedom of navigation and the rule of law in the face of China's unlawful territorial claim," he said. "For Japan's support for our peaceful, lawful, and principled approach, again we thank you."
Japan has no territorial claims in the South China Sea but is engaged in a separate bitter row with Beijing over tiny isles in the East China Sea.