AS the Philippines prepares to commemorate the 10th anniversary of its supposed 2016 arbitral victory against China, an unexpected critic has emerged, and it’s not Beijing: Malaysia.

Malaysia’s former foreign minister Saifuddin Abdullah recently argued that Manila’s decision to revive and internationalize the South China Sea arbitration has contributed to regional tensions, invited foreign intervention and undermined Association of Southeast Asian Nations (Asean) centrality. He urged the Philippines to embrace “quiet diplomacy” and warned against “making too much noise.”

His remarks may appear reasonable on the surface. But beneath the language of Asean consensus lies a more uncomfortable reality: Malaysia itself is hardly a neutral observer in the South China Sea.

For decades, Kuala Lumpur has quietly expanded and consolidated its presence in the southern Spratly Island Group.

Malaysia occupies several maritime features also claimed by the Philippines, including areas that fall within Manila’s exclusive economic zone. Some of these outposts have undergone reclamation and military development, though on a much smaller scale than China’s massive island-building campaign.

The irony is difficult to ignore.

Malaysia criticizes the Philippines for asserting its maritime rights through international law, yet it has itself strengthened its physical presence on disputed features while insisting that discussions remain behind closed doors.

The message appears to be that claims are acceptable as long as they are made quietly.

But for Filipinos, the issue extends beyond the South China Sea.

Saifuddin’s comments revived another unresolved question that has long lingered beneath Philippine-Malaysian relations: Sabah.

Malaysia strongly protested Manila’s 2024 submission to the Commission on the Limits of the Continental Shelf because the Philippine continental shelf projection partly relies on baselines connected to Sabah. Kuala Lumpur describes its sovereignty over Sabah as “indisputable.”

History, however, suggests otherwise.

The Philippines has never formally abandoned its claim to Sabah, which originated from the historic rights of the Sultanate of Sulu. While successive Philippine administrations have chosen not to aggressively pursue the issue in the interest of bilateral relations and Asean solidarity, the legal claim remains embedded in Philippine law and diplomacy.

This is where Malaysia’s position becomes vulnerable.

If Kuala Lumpur insists that historical claims and legal arguments should be set aside in favor of political pragmatism, then the same logic could apply to some of Malaysia’s own positions in the South China Sea.

Conversely, if Malaysia insists on the absolute legitimacy of its sovereignty over Sabah, then it cannot dismiss the Philippines’ own historical and legal narratives as irrelevant.

The result is an emerging diplomatic contest.

On one side stands the Philippines, increasingly relying on international law, arbitration and strategic partnerships to defend its maritime rights. On the other stands Malaysia, advocating quiet diplomacy, Asean mechanisms and cautious engagement with China.

Neither approach is inherently wrong.

Malaysia itself has repeatedly rejected China’s maritime claims and has filed diplomatic protests against Chinese incursions into its waters.

To suggest that the Philippines is responsible for escalating tensions risks misdiagnosing the problem.

The source of instability in the South China Sea is not the country that brought its case to international arbitration. It is the failure of all claimants to agree on a common ground to resolve the issue.

The Philippines and Malaysia have long enjoyed friendly relations, shared Asean values and common interests in regional stability. Yet friendship does not preclude disagree​ment.

If Kuala Lumpur chooses to publicly criticize Manila’s strategy, it should expect Filipinos to revisit difficult questions about Malaysia’s own actions in the Spratlys and the unresolved issue of Sabah.

Quiet diplomacy has its place.

But silence has never been the only path to defending national interests.

Ten years after the arbitral decision, the larger lesson may be this: Southeast Asian nations cannot selectively invoke international law when convenient and dismiss it when uncomfortable.

Whether in the West Philippine Sea or in Sabah, history and law have a way of returning to the table.