A Sunday visit to a Philippine province on the edge of the disputed South China Sea by U.S. Vice President Kamala Harris sends a clear and loud message to China: Washington is standing by the Philippines in the South China Sea disputes against China.

China considers the South China Sea its sea, including the energy resources hidden beneath it. And it has been doing whatever it takes to ensure control of the vast waterway, like intimidating its neighbors and building artificial islands in what the Philippines considers its waters.

That's despite protests from Manila and Washington, which in 2016 won an international arbitration ruling that China has no historic title over the waters of the South China Sea.

But Manila didn't have a clear and consistent policy to deal with China's aggression, as evidenced by several flip-flops in Rodrigo Duterte's administration. And Washington didn't openly declare its support for the Philippines against China's aggression either.

The U.S. vice president's visit to the disputed islands, the first high-ranking official to visit the region after the two allies won the international arbitration, signals a significant policy shift from Washington and the Philippines.

"The White House has been clear that it is committed to our alliances in Southeast Asia," Daniel Pickard, chair of Buchanan Ingersoll and Rooney's International Trade and National Security Practice Group, noted in an email to International Business Times. "The Vice President's visit is occurring within the larger context of the Asia-Pacific Economic Cooperation (APEC) Leaders' summit, demonstrating an increased U.S. diplomatic and economic engagement in the Indo-Pacific."

Pickard believes that the vice president's visit is an explicit expression of Washington's disapproval of China's actions in the area. "The South China Sea dispute has significant military and economic implications. Therefore, the vice president's visit is a strong signal in support of the Philippines as to their ongoing dispute with China," he added.

Ambrose Conroy, chief executive officer of Seraph, a supply chain consulting firm, provides further insight into the economic implications of the dispute, mainly about the energy resources hidden below the South China Sea. "Sustaining China's industrial-driven economy requires massive energy," he told IBT. "China can't produce the energy it needs while leaders are working opportunistically to solve that bottleneck."

The South China Sea energy resources are a solution to the problem. "Both China and the Philippines are eyeing the South China Sea as an energy solution," Ambrose said. "VP Harris' visit to the Philippines is both a clear reminder of the U.S. support and a continuation of Chinese containment that began with former President Trump's tariffs and recently manifested in President Biden's embargo of crucial semiconductor equipment."

U.S. President Joe Biden and Vice President Kamala Harris attend a reception in Philadelphia