Last month the Pentagon sent a tough signal to its fastest-growing rival in Asia when a U.S. Navy warship sailed close by an artificial Chinese island in the contested waters of the South China Sea.

The message: The U.S. will stand by its allies as they confront China's increasingly muscular military.

This month, the Defense Department picked Joint Base Lewis-McChord for a friendlier exchange between the two world powers.

The Army is opening up the South Sound base for a weeklong exercise with its Chinese counterpart, the People's Liberation Army.

It's fairly small compared with some of the standard engagements that pull JBLM soldiers all over the Pacific. Only 80 Chinese soldiers are expected to visit JBLM.

But it's significant because it will be the first time ground-level Chinese soldiers visit an Army base in the continental U.S. for a military-to-military exercise.

"It's a big deal," said Timothy Heath, a China expert at the Rand Corp. "It's a sign of an improving security relationship that needs more stability. This is a good sign. We need exercises like this to promote stability."

For the Puget Sound area, the exercises come at a time of increased relationship-building with China. President Xi Jinping visited the region, including Tacoma's Lincoln High School, in September. Chinese investors have proposed building a high-rise hotel next to Tacoma's convention center downtown. And China remains Washington state's largest export market.

The U.S. and Chinese militaries aren't ready to play war games together and they won't practice offensive maneuvers that could be used against American allies on JBLM training grounds. That's something the Army offers to its closest allies in the Pacific, such as Japan, and most recently, India, during joint exercises in Washington state.

Instead, American and Chinese troops will try to find common ground in their preparations for natural disasters in a weeklong exercise Monday through Nov. 21 that will unfold both in Seattle and at JBLM, said Lt. Col. Jason Shelton, who is coordinating the exercise as a planner on the I Corps staff.

The event is one in a series of 11 annual exercises that have joined the two armies for discussions on how they might respond to humanitarian crises. The others have taken place in Washington, D.C., Hawaii and in different parts of China.

"Despite our differences with China, we can still work together and come together to work on common challenges, such as natural disasters and humanitarian crises," Shelton said.

In this case, they're gaming out how they could collaborate to help civilians in a severe earthquake.

It's a worry that both countries share, with China preparing for disasters in the Himalayas and Northwest military leaders drawing up plans for a catastrophe on the Cascadia Subduction Zone off the coasts of Washington and Oregon.

Ideally, Washington National Guard Commander Maj. Gen. Bret Daugherty said, both countries could partner to respond powerfully in a crisis, such as a typhoon or tsunami.

He gave a presentation at Camp Murray in May to a visiting Chinese general on local earthquake preparations. He's also sensitive to the relationship between the two countries because he has family ties to the Commonwealth of the Northern Marianas, a U.S. territory in the South Pacific where Chinese and American interests sometimes clash.

"We need to figure out how to work with them and there could be good news that comes out of that partnership, especially along the lines of disaster relief," Daugherty said.

Normally, JBLM hosts contingents from foreign militaries that have competing interests with China. Those exchanges have accelerated since JBLM's I Corps headquarters returned from its last deployment to Afghanistan in 2012 and the Army turned JBLM into a central player in its "Pacific pivot."

The Japan Self Defense Force sends a battalion every year to train at JBLM's Yakima Training Center. That country is boosting its defense budget to pace itself with China's growth and preparing for conflicts on islands that both it and China claim.

On its latest exercise in Yakima, Japanese forces practiced helicopter assaults with troops from JBLM's 7th Infantry Division.

South Korea, likewise, has an officer assigned to JBLM's I Corps and has sent large numbers of soldiers to training events with JBLM troops in California. It, too, has an island dispute with China.

Other militaries that fall within China's orbit -- such as Australia, Taiwan and Singapore -- also regularly connect with JBLM's leaders.

But Heath of the Rand Corp. said those nations probably support the U.S. Army's welcome to the People's Liberation Army because they believe every side would suffer if a war breaks out in the region.

"Our allies and partners want a strong defense relationship with the U.S., but they also want to see stable relationship between U.S. and China," said Heath, a former adviser to the Pentagon's Pacific Command in Hawaii, where he focused on China issues. "They do not want to see the U.S. and China go to war over something reckless."

U.S. Pacific Command participates every year in more than 40 military exercises with Chinese forces, said PACOM spokesman Maj. Dave Eastburn.

Those exercises take place despite the sometimes harsh words the countries exchange.

Late last month, the U.S. Navy prodded China on a patrol through the South China Sea, where China has reclaimed thousands of acres of land to expand what appear to be military bases in waters widely considered as international trade routes. Those islands have exacerbated conflicts with neighbors such as Vietnam, Malaysia and the Philippines.

U.S. Rep. Denny Heck, D-Olympia, says the new defense budget includes a provision requiring the Pentagon to study how it would send ground troops to island conflicts in the South China Sea.

"There's no question this is an existential threat to the geopolitical order, and therefore, there's no question JBLM will be involved" in addressing the conflict, Heck said at a local forum Thursday.

Defense experts, however, say Chinese and American ground forces are unlikely to face off against each other; most conflicts, they say, center on potential battles at sea, in the air or even in cyberspace.

"Traditionally, in my time when I worked at (Pacific Command) it seemed like the Army had an easier time connecting with their Chinese counterparts, and I think this exercise reflects that," Heath said.

Army leaders say each year's joint disaster exercises have grown increasingly complex. A lot of the work this time is expected to take place in a mock headquarters and at "tabletop" exercises for a major earthquake.

On the ground, some drills are scheduled linking medics and supply experts from both countries. They'll practice emergency relief in the field, and they may come away with good memories of one another.

"They really laid out the red carpet for us in China," said Sgt. Maj. Mark Swart, who supervised soldiers in China's Guangzhou Military Region in the last disaster exercise.