U.S. Vice President Joe Biden is in China for talks expected to focus on Beijing's controversial air defense zone, which includes islands also claimed by Japan.
Biden arrived Wednesday in Beijing, where he has promised to raise the issue during his meetings with Chinese President Xi Jinping and other top leaders.
His one-day visit began at the U.S. Embassy, where he encouraged a group of Chinese visa applicants to "challenge the government."
"Innovation can only come when you can breathe free, challenge the government, challenge your teachers, challenge religious leaders."
Following a later meeting with his counterpart Li Yuanchao, Biden said the U.S.-China relationship was "hugely consequential" and "complex," and requires "sustained, high-level engagement."
The trip comes a day after a visit to U.S. ally Japan, where he said he was "deeply concerned" at China's Air Defense Identification Zone in the East China Sea.
After meeting Japanese Prime Minister Shinzo Abe, Biden suggested establishing "confidence building measures, including emergency communications channels" to help reduce tensions.
Joseph Cheng, a political science professor at the City University of Hong Kong, tells VOA that such measures could be welcomed by both sides.
"Some kind of hotline is definitely possible. I think all parties concerned welcome this. And further discussions on confidence building measures are to be welcomed. Ideally, there should be some sort of code of conduct along the lines of that concluded between China and ASEAN."
But Cheng does not expect Biden to take on a formal mediating role, since China has been reluctant to involve outside powers in what it views as bilateral territorial disputes.
Further dialogue could also be complicated by Japan's refusal to formally recognize a dispute over the islands, something it views as a weakening of its position.
Bonnie Glaser, a China expert at the Washington-based Center for Strategic and International Studies, tells VOA that Biden finds himself in a tough position.
"It is quite difficult for Vice President Biden in this particular heightened, tense atmosphere, to try and urge the two sides to resume political dialogue and particularly to talk about confidence building measures between the two militaries."
China late last month set up its Air Defense Identification Zone. Beijing has requested that all airplanes submit flight plans ahead of flying through the zone.
The U.S. has repeatedly rejected the Chinese zone. Last week, it flew two unarmed B-52 bombers on "routine" training missions through the area, ignoring Chinese demands the aircraft identify themselves.
While Beijing said it monitored the B-52 flights, it did not interfere. Later, however, it did scramble fighter jets to the area, heightening concerns about a possible miscalculation in the air.
Ahead of Biden's arrival, China's Defense Ministry said its determination to defend the zone are "unwavering, and the military is fully capable of exercising effective control" over the area.
The state-controlled China Daily newspaper also warned in an editorial Wednesday that Biden "should not expect any substantial headway if he comes (to China) simply to repeat his government's previous erroneous and one-sided remarks."
After visiting China on Wednesday, Biden will head to South Korea Thursday, which has also been angered by China's declared air defense zone.
He is expected to meet with President Park Geun-hye and visit the demilitarized zone with the North before returning to Washington.