HANOI (Reuters) - U.S. and Chinese defense chiefs locked horns over U.S. arms sales on Taiwan on Monday as they met for the first time since Beijing lifted a freeze on U.S. military ties.

U.S. Defense Secretary Robert Gates called the meeting with his Chinese counterpart, Liang Guanglie, constructive and accepted an invitation to visit China next year. But China said both acknowledged ""problems and obstacles"" in military relations.
Top among them, in China's view, are U.S. arms sales to self-ruled Taiwan, a nearby island Beijing considers a renegade province.
Beijing cut off defense ties earlier this year in protest against the Obama administration's proposed $6.4 billion arms package to Taiwan and U.S. officials warned of a heightened risk of misunderstandings between the two nations' militaries.
The new-found thaw is tentative and, U.S. officials acknowledge, incomplete.
Gates said the U.S. military had nothing to do with what was ""fundamentally a political decision"" by the Obama administration and past U.S. governments to sell weapons to Taiwan, and that defense ties should not suffer as a result.
The United States switched diplomatic recognition from Taipei to Beijing in 1979, recognizing ""one China."" But the United States remains Taiwan's biggest arms supplier and is obliged by the 1979 Taiwan Relations Act to help in the island's defense.
""Why the military relationship should be held hostage to what is essentially a political decision seems to me curious,"" Gates told reporters. ""And I believe it should not be. If there is a discussion to be had, it is at the political level.""
Guan Youfei, deputy director of the external affairs office of China's Defense Ministry, told reporters after the meeting: ""Minister Liang pointed out that arms sales to Taiwan were an impediment to wider and deeper bilateral defense relations.""
U.S. officials including Gates have expressed frustration with the on-again, off-again relationship with China's military, whose rapid buildup has raised eyebrows in Washington. A Pentagon report released in August said Beijing was expanding its military edge over Taiwan, increasing the lethal capability of its short-range ballistic missiles.
Gates noted that U.S. President Barack Obama and Chinese President Hu Jintao had given clear directions to improve the ""underdeveloped"" military-to-military relations. ""My hope is that today's meeting will inaugurate that process,"" Gates said.
--Territorial disputes
U.S. arms sales to Taiwan have added to a litany of strains between the world's biggest and second-biggest economies, including the value of China's currency, trade protectionism, Internet freedoms, human rights and Tibet.
Gates also raised eyebrows with a public speech he made on Monday in which he indirectly challenged China's insistence on a bilateral approach to territorial disputes. Gates and Liang will attend Asia-Pacific defense talks on Tuesday.
""Relying exclusively on the bilateral relationships is not enough -- we need multilateral institutions,"" he told an audience at Vietnam National University.
---- Photo: Defense Secretary Robert Gates, right, is greeted by senior Vietnamese military officials as he arrives at the Noi Bai International Airport in Hanoi, Vietnam, Sunday, Oct. 10, 2010. (Photo: Carolyn Kaster, Pool)