( The Wall Street Journal) DALIAN, China—China is seeking greater access to U.S. aircraft carriers and guidance on how to operate its own first carrier, the Liaoning, testing the limits of a newly cooperative military relationship the two sides have tried to cultivate in the past year.

The latest Chinese request came last week when U.S. Adm. Jonathan W. Greenert, chief of naval operations, visited China to explore new areas of cooperation, despite recent maritime tensions and the presence of an uninvited Chinese spy ship at naval drills off Hawaii.

China’s navy chief, Adm. Wu Shengli, suggested the U.S. should bring the USS George Washington, an aircraft carrier based in Japan, to a mainland Chinese port and allow the crew of the Liaoning to take a tour, according to Adm. Greenert.

“Admiral Wu wants to work on that,” Adm. Greenert told The Wall Street Journal in an interview at the end of his trip, which included a tour of the Liaoning.

“He’d like his crew to get a tour of the George Washington and have the George Washington crew, a gaggle of them, come to the Liaoning,” he said. “I’m receptive to that idea.”

A U.S. carrier’s visit to China—possibly Shanghai—could happen within a year if Adm. Wu formally proposed it and won support for the idea from policy makers on both sides, he said.

China’s defense ministry didn’t respond to a request for comment.

The carrier discussions highlight a counterintuitive trend in China-U.S. relations: Military ties are improving, especially between the navies, even as China seeks to enforce maritime claims in Asia that are contested by neighbors, including U.S. allies.

Adm. Greenert has met his Chinese counterpart three times in the past year and will meet him again in September—a reflection, he says, of the commitment to improve military ties made at last year’s summit between Presidents Xi Jinping and Barack Obama.

But the discussions over the carriers also raise questions for both sides about how far they will go in allowing each other access to sensitive technology, and whether such exchanges will in fact reduce tensions at sea.

This month, China sent an uninvited spy ship to monitor continuing U.S.-led naval drills off Hawaii, even though the Chinese navy is participating in the exercises for the first time in another attempt by the U.S. to improve ties.

During the drills, a delegation of Chinese navy officers visited another U.S. carrier, the USS Ronald Reagan, while at sea, according to a spokesman for the Pacific Fleet.

U.S. officials say the Chinese spy ship is operating legally in international waters, much as U.S. spy ships do around China’s coast. Adm. Greenert declined to comment on the Chinese spy ship’s activity, saying it was an operational matter.

China’s carrier, launched in 2012 and based on a hull bought from Ukraine, is particularly sensitive as carriers are predominantly offensive platforms, and U.S. officials say the Liaoning could be used to enforce Chinese territorial claims. The Pentagon also says China will likely build multiple indigenous carriers over the next decade.

Adm. Greenert said Adm. Wu earlier suggested organizing meetings between Chinese and U.S. carrier aviation personnel to discuss “details on maintenance and tactics.”

“That was deemed to be inappropriate by our folks, our policy folks, so we set that aside,” Adm. Greenert said.

One obstacle is U.S. law, which forbids any cooperation with the Chinese military—including even some verbal exchanges—that might allow China to gain U.S. military know-how. And some in the U.S. defense establishment argue that China shouldn’t be rewarded for its recent assertive behavior.

Adm. Greenert sees the issue differently, arguing that his priority is to build trust and try to shape the behavior of a Chinese navy that will inevitably grow stronger, rather than to raise repeated protests over individual incidents.

“If all we do is state that over and over, day in day out, the reality is our ships are operating in the same area and we have to figure out how to manage our way through this,” he said.

He said he didn’t raise last week the issue of a Chinese oil rig recently deployed in waters claimed by Vietnam in the South China Sea, or other Chinese activities in disputed waters.

“I didn’t go into that with an agenda item because I didn’t want to get bogged down in a bunch of platitudes or for-the-record statements because we only had so much time,” he said, adding that U.S. officials had raised those issues in separate meetings.

“I wanted to get a clarity of purpose. Where are you on this, Admiral Wu? Are you ready to move forward? And then, as his guest, see what I could see that he was willing to show me on the platforms.”

Adm. Greenert said he tried to build on eight proposals for cooperation made by Adm. Wu last September. One was China’s attending the naval drills off Hawaii. Another was implementing a code for unplanned encounters at sea, or CUES, signed by 21 Pacific naval powers in April.

Some Chinese officials have suggested the code didn’t apply in disputed waters around China’s coast, but Adm. Greenert said Adm. Wu had committed last week to observing CUES throughout the South China Sea.

Adm. Greenert said he had seen no reports of harassment or unprofessional behavior in encounters between U.S. and Chinese ships since April. “We’re talking more. They’re speaking English,” he said. “It’s a civil tone—it’s good.”

He also said he met for the first time last week with China’s State Oceanic Administration, which oversees the coast guard, and discussed whether they, too, could observe elements of CUES.

“They were open to the concept and saw the value in pursuing it,” he said of the officials overseeing the coast guard, which has often been used to enforce China’s maritime claims.

Other areas of proposed cooperation include sending officers to each other’s naval academies and war colleges, and arranging simple joint exercises at short notice in the Gulf of Aden, the Mediterranean, the South China Sea and the East China Sea, he said.

Adm. Greenert said China was reciprocating in terms of access to ships, having shown him the Liaoning, a frigate, a missile patrol boat and a Type 039B diesel-powered submarine last week.

He said allowing the Liaoning crew to tour a U.S. carrier wasn’t “revolutionary,” as the U.S. had taken Chinese military personnel on board its carriers for several years.

Following his tour of the Liaoning, he said he met about 180 of its crew, who questioned him about how to certify carriers as seaworthy after maintenance, and how to lead a strong naval aviation wing.

Adm. Greenert said he asked the crew which U.S. ports they would like the Liaoning to visit, and some said Hawaii. “When that carrier’s ready to go out and underway, visiting Pearl Harbor may be a natural progression,” he said.

He conceded, however, that some of his proposals might meet opposition in Washington, and much depended on China’s actions in the next few months.

“If you and I sit down a year from now and you say how’s it going, and I’ve got a bunch of excuses why none of this is going anywhere, then I’d say somebody’s been dragging their feet here,” he said.

“I think we’ll understand the genuinity of each other as we’re looking forward. I should be upfront though: We don’t make all the rules, so when I go forward with wanting to do this, we’ll see what the policy folks want.”

By Jeremy Page, July 21, 2014 in The Wall Street Journal