"China will never seek hegemony or expansionism," he said, adding that China will continue to "open the door to the outside".

"China's development is not self-centredness and will not do harm. It is not an 'I win and you lose' path. China is neither a challenge nor a threat," he said.

There have been rising nationalistic calls on the mainland for China to act tougher in its diplomacy, especially towards countries involved in territorial disputes with Beijing.

Xi, in the middle of diplomatic tussles that involve Japan, Vietnam, the Philippines and the United States, seems to have taken heed of such sentiments.

In September, he described the Japanese government's move to purchase three of the disputed Diaoyu Islands, known as the Senkakus in Japan, as a "farce" and "fascist" behaviour.

Professor Wang Fan, from Beijing Foreign Affairs University, said there were "a lot of concerns about whether Beijing will set out on a new diplomatic path that does not stress peaceful development … and Xi wanted to allay such fears".

But Wang said the line should not be taken as a sign that Xi would refrain from warning other countries seen to be disregarding China's interests.

In a speech made after being named party general secretary, Xi vowed to "work hard for the great revival of the Chinese nation", and he reiterated that pledge later in Beijing. His predecessor Hu had earlier said that China should become a maritime power.

"I will mount a long wind some day and break the heavy waves," Xi said, repeating a line by Chinese poet Li Bai and hinting that China is confident of reaching its goals.

In a meeting of the party's outgoing and incoming Central Military Commissions last month, Xi asked military leaders to improve the army's deterrence and fighting capabilities.

Yang Xiyu, a senior research fellow at the China Institute of International Studies, said Xi was well aware of nationalistic feelings on the mainland.

"He knows well that it is important to stay attached and act in accordance with public feelings," he said. "Xi's background as the son of a former revolutionary, but one who also lived a grass-roots life after being sent to the countryside, has somehow shaped his views."

Xi's is known for talking tough. In Mexico in 2009, Xi hit out at concerns over China's development.

"Some well-fed foreigners have nothing better to do but to point fingers at us," he said. "First, China doesn't export revolution. Second, it doesn't export famine and poverty, and third, it doesn't mess around with you."

Lin Wen-cheng, director of the Institute of Mainland China Studies at Taiwan's National Sun Yat-sen University, said Xi's ties with the army gave him more flexibility in diplomacy.

Xi was the secretary to then defence minister Geng Biao in the 1980s, and accompanied Geng on a trip to the Pentagon.

Professor Jin Canrong, an international affairs expert at Renmin University, said Xi's family background has made him more determined.

Xi's father, Xi Zhongxun, a communist guerrilla leader, was purged during the Cultural Revolution, when the younger Xi was sent to the countryside. He chose to "survive by becoming redder than the red", a US diplomatic cable released by WikiLeaks said.

Xi turned to serious politics, joining the party in 1974 when his father was still in jail, and he later joined the army, during which time he "wore his uniform every day". Xi was "exceptionally ambitious", confident and focused, and had his "eye on the prize", the cable said.

"With such a background, Xi will be tougher than Hu and won't wait to act," Jin said.

But Xi is also familiar with the West. During a trip to the US in February, he chatted with farmers he met in 1987 and showed his liking for Hollywood movies.

"Xi knows how to draw the line between being tough and friendly," Lin said. "He knows Western leaders are popular for their down-to-earth image. He is willing to act that way."