U.S. Defense Secretary Chuck Hagel wrapped up the ASEAN defense ministers gathering Thursday, saying the group held "an extremely valuable meeting here in Hawaii."

Hagel said the meeting with the 10 defense officials from the Association of Southeast Asian Nations "affirmed the deepening bonds of friendship between our nations and the growing opportunities that exist for us to partner together."

Natural disasters and humanitarian crises "will be the defining security challenges of the 21st century," Hagel said at a news conference at the Kahala Hotel and Resort.

That statement was underscored by the lifting of a tsunami warning in Hawaii just hours before an ASEAN round-table discussion Wednesday on climate change and the Pacific’s vulnerability to natural disasters at the National Oceanic and Atmospheric Administration’s Daniel K. Inouye Regional Center on Ford Island. The warning was prompted by a magnitude-8.2 earthquake that hit northern Chile.

Singapore proposed using its Changi Naval Base as a regional humanitarian assistance, disaster relief crisis coordination center, Hagel said.

"This could be an important venue for nations in the region to coordinate military responses to disasters, and it’s an idea that we’re going to pursue," he said.

ASEAN is made up of 10 member nations: Indonesia, Malaysia, the Philippines, Singapore, Thailand, Brunei, Vietnam, Laos, Burma and Cambodia.

The three-day session in Honolulu was the first time the United States has hosted an ASEAN defense ministers meeting.

Hagel called the gathering "an important milestone in America’s growing engagement with the ASEAN nations, and another signal of the important role ASEAN has to play in promoting regional stability and prosperity."

None of the foreign defense ministers, including Malaysian Minister of Defense Dato’ Seri Hishammuddin Tun Hussein, whose country still is trying to determine how Malaysia Airlines Flight 370 vanished, made public comments during press events.

Thursday’s discussions with ministers addressed a range of regional security issues, including improving maritime security cooperation as well as tensions in the South China Sea, Hagel said.

"I told the ministers that the United States is increasingly concerned about the instability arising from the territorial disputes in the South China Sea," he said without mentioning China.

It’s important that all claimants "avoid the use or threat of force or intimidation or coercion," said Hagel, who will leave Hawaii on Friday for Japan, China and Mongolia.

The Associated Press reported Thursday that the U.S. has struck a more robust tone regarding China’s maritime behavior in recent weeks. A diplomat cautioned China in congressional testimony that America will meet its defense commitments in the South China Sea.

"There should be no doubt about resolve of the United States," Assistant Secretary of State Daniel Russeltold a Senate panel Thursday, noting China’s "intimidating steps" toward the Philippines, the news agency said.

Hagel also addressed the shootings Wednesday at Fort Hood, Texas.

"I’ve been staying in touch with Army leaders, our senior (Defense Department) leaders, and will continue to do so," he said. "We need to let investigators do their work to help us all understand exactly how this happened."

Hagel said the Defense Department already was implementing recommendations made from reviews following last year’s Washington Navy Yard shooting, in which 13 people died.

"As the Fort Hood investigation unfolds, we will continue to take a close look to identify any new lessons learned and implement those, as well," he said.

Spc. Ivan A. Lopez, 34, who shot and killed three others and took his own life Wednesday, had been under psychological treatment, the military said.

Hagel said the latest shooting shows there’s still something wrong with the system.

"Obviously, we have a gap," he said.

Asked why American military bases seemingly have become so dangerous, Hagel cautioned that there are a lot of bases, "and there are a lot of safe places, too."

"And I think we have to be careful not to jump to any conclusions or try to frame this up in some kind of a social statement," he said. "We just don’t know enough yet."