A meeting between U.S. Secretary of Defense Ashton Carter and his Southeast Asia counterparts kicked off in Hawaii on Friday with a show of air power as the U.S. seeks to strengthen security ties in the volatile South China Sea region.

As part of the informal meeting, the 10 defense ministers of the Association of Southeast Asian Nations toured a collection of U.S. aircraft at Joint Base Pearl Harbor-Hickam and then witnessed a flyover featuring two F-22 Raptor fighters and a B-1B bomber.

The two-day event takes place as China continues to fortify its position in the South China Sea, transforming coral atolls into concrete islands with defense installations in the face of claims of territorial sovereignty by several Southeast Asian nations.

During a midday news conference at the Aulani, a Disney Resort &Spa in Ko Olina, Carter said the meeting was already proving fruitful in strengthening the region’s security network.

“The U.S.-ASEAN partnership is now stronger than ever,” he declared.

Carter said the U.S., for its part, not only plans to help bolster ASEAN’s defense profile in the Asia-Pacific region, it also wants to upgrade its own force posture in the area.

He said the effort is part of the Obama administration’s campaign to “rebalance” its security interests to the Pacific and Asia after focusing on the other side of the Atlantic for many years.

“The U.S. rebalance and burgeoning security network are important in a time of regional change and challenges,” he said.

Carter said the group discussed this summer’s international tribunal ruling that found that China’s claims to historic rights across much of the South China Sea are invalid. The ruling by the Permanent Court of Arbitration has been ignored by China, as have previous judgments against it.

“The United States stands by the matter of principle involved here,” Carter said, adding that it’s a principle of adherence to the law and the avoidance of militarization and coercion.

“As for our own activities,” he said, “I think I’ve made it abundantly clear for quite some time: The United States will conduct its activities around the world as we have in the past, into the future, with no change.”

Carter said the ministers reaffirmed their commitment to keeping the region’s waters open and secure and decided to go further in improving coordination and cooperation among collective militaries and coast guards of the various nations.

“We discussed specific ways how ASEAN nations can work among themselves … and with the United States to increase security in these vital waterways,” he said. “It’ll help us all to connect, to cooperate and to contribute to regional security.”

Carter invited the ministers to several future conferences and events, among them a “maritime domain awareness exercise” next year to be coordinated by Adm. Harry B. Harris, commander of U.S. Pacific forces.

The ministers also talked about the growing threat of terrorism in the Asia-Pacific region. Carter said the gathering discussed threats of Islamic State-affiliated groups and other extremist organizations.

“We resolved to work together,” he said.

During the news conference, Carter reacted to the statements made earlier Friday by Philippines President Rodrigo Duterte, who shocked many when he compared himself to Adolf Hitler and the Holocaust and said he would be happy to slaughter 3 million drug users in his country.

“Just speaking personally for myself, I find these comments deeply troubling,” Carter said.

Carter said the issue was not discussed at the meeting Friday. He did say he and his counterpart from the Philippines, Delfin Lorenzana, talked about continuing the alliance between the two countries.

Cooperation between the U.S. and the Philippines has served the interests of the two nations for many years, he said.

“The alliance is made up of independent and strong nations,” the defense secretary said. “It depends on the continuation of a sense of shared interest. So far in U.S.-Philippines history, we’ve had that and we look forward to continuing that.”

Duterte came to power in June, pledging to fight crime and drugs, and the Philippines has seen a surge in killings of drug suspects. Officials have counted about 3,000 deaths during the crackdown, nearly a third by police.

Elsewhere, the comments by Duterte were condemned as inappropriate and offensive by many, including the World Jewish Congress.

The comments are the latest in a series of controversial statements by Duterte. Earlier this month, President Obama canceled a meeting with Duterte when the Philippine leader directed an expletive his way.

During Friday’s activities in Hawaii, the ASEAN ministers watched a demonstration of a helicopter boarding a ship in a search and seizure operation.

Later, they were offered the opportunity to board some of the military aircraft at Hickam Field, some of them quite capable of patrolling the vast waters of the South China Sea.

Friday’s events concluded with a dinner aboard the battleship Missouri. Included in today’s itinerary is a tour of the destroyer USS Chung-Hoon.