China and the United States began their second day of sensitive defence talks on Saturday after warnings from Beijing that US arms sales to Taiwan were a major obstacle to easing tensions.
The defence contacts -- the first between the world powers for five months after China cut military exchanges over a proposed US arms package to Taiwan -- raised hopes of an easing of lingering tensions.
But the head of the Chinese delegation signalled from the start of the talks that Beijing would be taking a tough stance, saying there were problems between the two sides and it was up to the United States to fix them.
"China-US military relations remain in a difficult period. We expect the US side to take concrete measures for the resumption and development of our military ties," Qian Lihua, co-chair of the talks and defence ministry press director, said Friday in comments quoted by the state-run Xinhua news agency.
Deputy Assistant Secretary of Defence David Sedney -- the head of the US delegation -- was due to brief reporters later Saturday.
One issue that was expected to be raised was whether the suspended military exchanges would officially resume, after Qian warned Friday they might not.
He emphasised that the two days of talks in Beijing did not mean that regular exchanges -- such as talks at a more senior level and disaster relief coordination efforts -- would automatically start again.
"Frankly speaking, it will take a long time to restore our military exchanges as not a single obstacle in military ties has been removed so far," Qian said, specifically mentioning arms sales to Taiwan.
The situation of Taiwan, a democratically-ruled island claimed by China, has long been one of the most sensitive issues in Sino-US relations.
The planned 6.5-billion-dollar US arms package that derailed military exchanges could still go ahead, and if it does, Taiwan would receive advanced weaponry including 30 Apache attack helicopters and 330 Patriot missiles.
Sedney, who was also due to meet with Ma Xiaotian, deputy chief of general staff of the Chinese army, said Friday he was looking to improve dialogue between the two sides, according to Xinhua.
"We must increase communications to reduce the chance of strategic misunderstanding," Xinhua quoted Sedney as saying.
Taiwan and mainland China have been governed separately since they split in 1949 at the end of a civil war, but Beijing sees the island as part of its territory awaiting reunification, by force if necessary.
Both sides have stationed vast weaponry on either shore of the Taiwan Strait.
Sino-US military relations remain marked by deep tensions over other issues aside from Taiwan.
Mistrust has grown as China has poured money into modernising its armed forces in recent years, fuelling concerns in the United States that it plans to project its power more boldly in the region.