It was not too long ago that China's new leaders were widely praised for adopting a fresh and self-confident foreign policy. Since Hu Jintao, China's president, took over the diplomatic portfolio in March 2003, Beijing has demonstrated a rare willingness to use its growing influence in promoting east Asian economic integration and security.

Yet, in recent months, China's much-lauded “new diplomacy” has lost momentum. The self-confidence that many countries welcomed from Beijing has been replaced with the old clumsiness and bombastic rhetoric. For example, China reacted harshly to the visit by Lee Hsien Loong, Singaporean prime minister, to Taipei in July, even though Mr Lee went in his private capacity and before becoming prime minister. By overreacting, Beijing risks alienating Singapore's new leader and looking like a bully.

China's relations with Japan, already at a 10-year low point, have deteriorated further in recent months. China's ill-timed exploration for natural gas in the East China Sea area claimed also by Tokyo provoked a fresh bilateral row. In the Asian Cup soccer matches in China in August, Chinese fans relentlessly booed Japanese players. Beijing downplayed this incident; but not one Chinese leader publicly condemned the fans' behaviour and China's image in Tokyo has suffered.

Even Beijing's relationship with the US seems to be fraying. Unhappy with Washington's quick endorsement of the inaugural speech of Chen Shui-bian on May 20 - despite the Taiwanese president's effort to tone down his pro-independence agenda - Chinese leaders have since pressed the Bush administration to suspend arms sales to Taiwan. High-level meetings, such as on the recent visit to Beijing by Condoleezza Rice, the US national security adviser, were wasted on Chinese preoccupations about Taiwan instead of focusing on substantive issues. Such disarray in Beijing's diplomacy may have affected China's handling of the North Korean nuclear stalemate. After hosting three rounds of fruitless talks, China appears unable to broker a real deal, raising doubts about its commitment to a proactive internationalist agenda. The confident tone in official Chinese rhetoric has disappeared as well. Mr Hu embraced the idea of “China's peaceful rise” in a speech in March. Since then, the phrase has been quietly dropped from official pronouncements. Some senior leaders are said to have objected to it as a potential constraint on Beijing using force to prevent Taiwan's independence.

The most obvious cause of these diplomatic missteps is the intensifying power struggle in Beijing. It is an open secret that Jiang Zemin, the nominally retired former leader who remains commander-in-chief, has been attempting to preserve his influence even at the expense of Mr Hu's authority. Distracted, if not weakened, by internecine intrigue, China's new leaders lack the political capital to maintain the momentum of the “new diplomacy”.

At a deeper level, there are two contradictions between the internal dynamics of China's system and the requirements of an internationalist foreign policy. First, to the extent that Chinese nationalism provides legitimacy for the Communist party, Beijing's leaders will be constantly tempted to sacrifice long-term diplomatic objectives for short-term political gains. Sadly, Chinese conservatives are far more adroit at exploiting popular nationalist sentiments than their more liberal-minded colleagues and thus put the latter on the defensive, especially over Taiwan and Japan.

Second, a liberal internationalist foreign policy is incompatible with China's illiberal domestic order. Although an illiberal regime can occasionally demonstrate tactical brilliance in diplomacy, its execution of a constructive, long-term foreign policy will be undermined by the character flaws inherent in autocracies: insecurity, secrecy, intolerance and unpredictability. Viewed from this perspective, the recent reversals in China's diplomacy should come as no surprise. They merely underscore again how China's closed politics is hampering Beijing's quest for international respect.