The U.S. Secretary of State warned that Washington is obligated to defend the Philippines if Beijing ignores an international tribunal's ruling that invalidated its vast claims in the South China Sea.

The statement was issued by the US Embassy in Manila on Tuesday on the sixth anniversary of the decision by an international tribunal to rule in favor of the Philippines.

China has been involved in territorial spats with the Philippines and other Southeast Asian states since rejecting its ruling as a sham.

The PRC needs to cease its provocative behavior and abide by its obligations under international law.

The 1951 U.S.-Philippines mutual defense treaty states that an armed attack on Philippine armed forces, public vessels, or aircraft in the South China Sea would invoke the U.S.'s mutual defense commitments.

The busy waterway is believed to be rich in undersea gas and oil deposits and where an estimated $5 trillion worth of trade and goods are shipped through each year.

The flashpoint region has become a point of contention between the U.S. and China.

Washington has deployed its Navy ships and Air Force jets to patrol the waterway for decades, even though it has no claim to the waters. China accused the U.S. of interfering in an Asian dispute and warned it not to come.

The Philippine Foreign Secretary said Tuesday that the ruling of the international court of justice would be a pillar of the new administration's policy and actions in the disputed area.

The findings are irrefutable and no longer within the reach of denial or rebuttal. Manalo said that the award is done.

"We reject attempts to undermine it, even erase it from law, history and our collective memories," said Manalo, who did not name China but clearly allusion to it.

China would likely frown on the policy stance declared by Manalo for the administration of President Ferdinand Marcos Jr.

After Marcos Jr. took office in 2016 he put the ruling back on the back burner, as he was often critical of the U.S. security policy.

In a meeting in Beijing in the middle of the year, the Chinese leader told the Philippine leader that they wouldn't budge.

Marcos Jr. said he wouldn't allow any trampling of Philippine waters.

Marcos Jr. said in an interview that since China has refused to recognize the ruling, it won't help settle disputes with Beijing.

Marcos Jr. said that the only option was to engage with China.

There were calls for him to ask China to comply with the ruling and to reverse his approach to the disputed sea.

Dozens of left-activists and laborers protested in front of the Chinese Consulate in Manila, asking Beijing to respect the ruling of the International Court of Justice and to defend the country's sovereignty in the South China Sea.

That's right.

The report was contributed to by Associated Press journalists.