HONOLULU, Hawaii -- While the Indo-Pacific region is mostly ocean, land forces are crucial to ensure it remains free and open so nations can prosper, the region's top U.S. Army officer said Tuesday.

For 70-plus years, the region has flourished under an international rules-based order that allows access to seas and airways, fair trade and sovereignty, said Gen. Robert Brown, commander of U.S. Army Pacific.

As a result, Indo-Pacific is now home to over half of the world's megacities and seven of the eight fastest-growing economies.

About 100,000 ships also pass through the Strait of Malacca each year --- equal to roughly a quarter of the world's trade.

"Free and open; it demonstrates a commitment to a safe, secure and prosperous region that benefits all nations," Brown said during his speech to kick off the three-day Land Forces Pacific Symposium, hosted by the Association of the U.S. Army.

Ground troops, he said, help countries stay on course in a sea-dominated part of the globe.

"Land plays a critical role. The obvious is that people live on the land. There's a lot of blue, but they live on the land," he said, adding the region has seven of the world's 10 largest armies.

Some threats to the current system come from China, which seeks to be a regional hegemon and to displace the U.S. in its effort to gain global preeminence, according to the National Defense Strategy.

To do this, China uses its military, influence operations and predatory economics to coerce nearby nations to their advantage, the strategy states, while it also militarizes parts of the South China Sea.

The rogue regime of North Korea also remains a challenge with its "outlaw actions and reckless rhetoric" despite United Nation's censure and sanctions, the strategy says.

Last year, the White House reaffirmed a whole-of-government commitment to help economic and commercial engagement in the region.

Over $113 million will now seed new strategic initiatives in the region, such as U.S. private investment, improvements to digital connectivity and cybersecurity, sustainable infrastructure development as well as energy security and access.

A new U.S. development agency, the U.S. International Development Finance Corporation, was also created and is expected to be operational by October.

The corporation will have an increased investment cap of $60 billion to support economic development in emerging markets, such as those in the Indo-Pacific, according to a news release.

"We're building a team of teams and presenting challenges to our adversaries in the region like never before," said Maj. Gen. Susan Davidson, the U.S. Indo-Pacific Command's director for logistics, engineering and security cooperation.

Partnerships, especially those between armies, in the region can keep areas secure and shipping lanes open to feed ever-growing populations.

"The commerce that enables the markets to serve the food needs occur in a safe, stable and secure environment enabled by freedom of movement of goods, services, people and information from the bottom of the sea up to the satellites in space," she said.

Attacks by violent extremist organizations may also be prevented if nations worked closer together, Brown said.

A counter-terrorism center being developed in Singapore, he said, is an example of how nations can share intelligence.

"They're going to find a gap or seam if we don't work together, no doubt about it," he said of extremists.

Mother Nature also significantly torments the region, where seven out of 10 deaths from natural disasters occur, Brown said.

"When a nation commits land forces, boots on ground to a situation -- be it a humanitarian assistance or a conflict -- there's no greater commitment," he said.

Ground forces from across the region, for instance, were called in to help after the 2015 earthquake in Nepal that killed nearly 9,000 people.

"We had an incredible response from the entire Indo-Pacific region to help save lives," he said, adding 35 of the 36 nations in the region joined in those efforts.

He also pointed to last year's rescue operation of 12 members of a Thai soccer team, aged 11 to 16, and their coach who were trapped in a cave for 18 days.

He called it a "black swan" event, which occurs out of nowhere, but had 25 nations unite to help out.

"Together, we're very powerful," he said. "Together, we can keep a free and open Indo-Pacific. Together, we can ensure growth and stability for all our nations."