IN MY column in the print edition I argued that the huge improvement in relations between Taiwan and China since 2008 does not seem to have led to any new enthusiasm in Taiwan for political union with the mainland. The hope, I wrote, is that China's leaders will “enjoy the smoother relations and not ask where they are leading.”

That of course is also very much the hope in official circles in Washington. China has never renounced its threat to use force to “reunify” Taiwan one day, and America has strong—if vague—commitments to Taiwan's security. The island was once its “unsinkable aircraft-carrier” and a keystone of its security strategy in the western Pacific. That all changed as America switched recognition to China in 1979.

However, the Taiwan Relations Act (TRA) of 1979, passed just after it opened diplomatic relations with the People's Republic of China, obliges America “to consider any means to determine the future of Taiwan by other than peaceful means…a threat to the peace and security of the western Pacific and of grave concern to the United States.”

Two different sorts of questions have recently been raised about that and other promises contained in the TRA. A commentary published on March 1st by Rupert Hammond-Chambers, president of the US-Taiwan Business Council, a lobbying group, claims that “the American defence commitment to Taiwan continues to deteriorate.” As evidence it points to the delays in American approval of further arms sales to Taiwan. In particular, America is yet to agree to provide new fighter jets (F-16 C/Ds), as well as to upgrade Taiwan's existing “Indigenous Defence Fighters” and American F-16 A/Bs.

American arms sales to Taiwan are of course an extremely sensitive issue in US-China relations. Despite a TRA commitment “to provide Taiwan with arms of a defensive character”, America in 1982 issued its third “joint communiqué” with China. It said it “intends gradually to reduce its sales of arms to Taiwan.” So whenever new sales are made—as they were a year ago to the tune of more than $6 billion, China bridles. On that occasion it suspended high-level military contacts until January this year. 

Yet the 2010 package was in fact part of a promise originally made by George W. Bush in 2001. Mr Hammond-Chambers and a number of analysts in Taiwan argue that Taiwan's air defences are becoming dangerously aged, while China continues to expand and modernise its forces and weapons, including those pointing at Taiwan.

Officials in Taiwan say they were pleased that, when China's president, Hu Jintao, was in America in January, Barack Obama referred to the TRA at a press conference. They are always listening keenly to hear which is given greater prominence—the 1982 communiqué, or the TRA and the “six assurances” America gave Taiwan about arms sales in 1982.

There is a debate in Taiwan, too, about whether the F-16 C/Ds are really necessary and desirable, given the friction their sale might cause. Some argue that the appeal for new fighter jets is part of the government's effort not to appear soft towards China, and that a delay suits it quite well.

What would certainly not suit it is the argument made (behind a pay wall) in Foreign Affairs, an American policy journal, by Charles Glaser, a specialist in international relations. Exploring ways in which America can negotiate China's rise without conflict, Mr Glaser points out that a crisis over Taiwan could “fairly easily escalate to nuclear war”. So America “should consider backing away from its commitment to Taiwan”. This would “smooth the way for better relations” with China.

He acknowledges the risks of such a strategy. First would be the loss of American credibility entailed in abandoning a long-standing ally that is now a vibrant democracy to a Communist claimant its people show little sympathy for. Second, China might find “its appetite whetted” for further concessions. However, he argues “territorial concessions” (an odd phrase since Taiwan is not America's to concede) “are not always bound to fail.”

The fear in Taiwan is that, though such arguments are far from official American policy, they are gaining currency. But ever since 1979, American policy over Taiwan has been an exercise in calculated or accidental ambiguity. China has had to believe that America would intervene if it tried to take Taiwan by force. But America has had to leave just enough doubt about its intentions that Taiwan is not emboldened into a rash move that might provoke China into giving up on “peaceful reunification”. Mr Glaser may be helping those, like Mr Hammond-Chambers, who argue that those doubts are now too big.