A Taiwanese warship has set sail for the South China Sea “to defend Taiwan’s maritime territory,” a day after an international tribunal ruled against China’s claims to islands and undermined Taipei’s claims to the islands there.

On Tuesday, a tribunal in The Hague ruled that China has no historic rights in the waterway and sided with the Philippines that had filed the complaint.

It also ruled that Taiwan-controlled Taiping, the largest island in the Spratlys chain, was legally a “rock” that did not give it an exclusive economic zone, undermining Taiwanese claims to waters surrounding the island.

Taiwanese President Tsai Ing-wen rallied troops on the deck of a frigate on Wednesday, saying the Taiwanese are determined to “defend their country’s rights.”

The warship headed for Taiwan-administered Taiping island in the Spratly island chain from the southern city of Kaohsiung.

Taiwan’s government meanwhile rejected the ruling as “completely unacceptable,” saying it had no legally binding force since the tribunal did not formally invite Taipei to participate in its proceedings or solicit its views.

“The South China Sea ruling, especially the categorization of Taiping island, has severely jeopardized our country’s rights in the South China Sea islands and their relevant waters,” Tsai told soldiers on the deck of ship.

“This patrol mission will show Taiwanese people’s determination to defend their country’s rights,” she said, before disembarking from the warship ahead of its departure.

The Taiwanese Defense Ministry vowed to “firmly defend Taiwan’s territory and sovereignty” and said there would be no change to Taiwan’s claims in the strategic seas because of the ruling.

The ministry said it would continue to send aircraft and ships for patrol missions to the region and remain “highly vigilant” to protect national security.

Several countries, including Taiwan, Brunei, Vietnam, Malaysia and the Philippines, have overlapping claims over the South China Sea. The waters are believed to sit atop vast reserves of oil and gas.

Chinese Ambassador to the US Cui Tiankai on Tuesday warned of “conflicts and confrontation” in the waters following the verdict.

“It will certainly undermine or weaken the motivation of states to engage in negotiations and consultations for solving their dispute. It will certainly intensify conflicts and even confrontation,” he said.

China on Wednesday dismissed as “baseless” the Philippines’ claims of sovereignty in the South China Sea, saying the islands are “China’s inherent territory”.

“The Philippines’ territorial claim over part of Nansha Qundao (the Nansha Islands) is groundless from the perspectives of either history or international law,” Beijing said in a white paper.

In the new policy paper, China asserted its sovereignty over the islands and their surrounding waters and opposed other countries’ “illegal claims and occupation.”