BEIJING -- Xi Jinping heads to Russia on Friday on his first foreign visit as president amid signs he wants China to be more assertive in challenging U.S. leadership in Asia while looking for new energy sources to fuel the Chinese economy.

Since Xi became China's leader late last year, the country has notched up its feud with Japan over a set of disputed islands believed to sit atop petroleum reserves, while also contending with the U.S. and other Western powers at the U.N. over the conflict in Syria, Iran's nuclear program and the growing belligerence of nominal ally North Korea.

"I think that, clearly, under Xi, China is starting to move away from the defensive philosophy. As it grows into its role as a major power, we can expect China to be even more assertive," said Warren Sun, a Chinese politics expert at Australia's Monash University.

Xi, who became Communist Party chief in November and was formally named president last week, will visit Moscow to highlight trade ties and discuss Russian gas exports.

Yearslong talks over Russia providing as much as 68 billion cubic meters of gas per year in a new pipeline have bogged down over pricing. China already receives about 8 per cent of its crude oil imports from Russia via a pipeline to the northeastern city of Daqing. At a briefing this week, Chinese Vice Foreign Minister Cheng Guoping said the two countries would sign a new deal on oil and gas, but offered no details.

Xi's Russian visit offers few potential risks, but will be scrutinized for signs of his personal stamp on Chinese diplomacy. The two countries share an authoritarian bent and a common desire to curb Western dominance. Heads of state from China and Russia, the former leaders of the communist camp, have made a tradition of paying inaugural foreign visits to each other after taking power.

Ties between them have warmed in recent years and two-way trade rose by 11.2 per cent last year to $88 billion. China has shown revived interest in buying Russian Su-35 fighter jets and other sophisticated weaponry following years of friction over China's cloning of Russian military technology.

The two also are closely aligned diplomatically, despite competition for influence in the former Soviet states of Central Asia. China has been happy to follow Russia's lead at the United Nations in opposing outside intervention in Syria's bloody conflict.

Xi is to depart Russia on Sunday for Tanzania -- one of China's oldest African allies -- and then South Africa and Congo.

Hawkish Chinese foreign policy experts have called increasingly for more vigorous policies to close what they see as a glaring gap between China's massive economic power and its relatively slight diplomatic heft.

That's especially important if China is to ensure its growing overseas economic interests, especially its hunger for energy and other resources, according to a recent essay by Chen Xiangyang, a scholar at the China Institutes of Contemporary International Relations affiliated with China's main intelligence agency, the Ministry of State Security.

China "needs to take the lead in settling regional and international issues, especially those relating to China," Chen wrote in the newspaper China Daily.

The U.S. has long been the dominant military power in the Asia Pacific. But with its acquisition of increasing amounts of sophisticated weaponry and assertive moves to defend its territorial claims, Beijing is showing its willingness to upset the established order in the region.

Chief among China's quarrels in Asia is the continuing standoff with Japan over five uninhabited islets -- roughly midway between Japan's Okinawa and Taiwan -- known as the Diaoyu group in Chinese and Senkaku in Japan. The feud took a dangerous turn in September when Japan's government bought them from their private Japanese owners, and many credit Xi for taking a stronger and more sustained response than in past flare-ups.

Tensions over such conflicts swiftly abated in the past, but China under Xi has maintained a dogged presence near the Diaoyus with patrol ships that regularly confront Japanese vessels. Jet fighters from both sides have been scrambled in the area after the two sides accused each other of tailing patrol flights.

Evidence of Xi's firmer stance can also be gleaned from some of his few public statements before taking power, including remarks in 2010 to Chinese students in Mexico in which he fulminated against nosy foreigners who criticize China's human rights record. More recently, he told the party's 25-member Politburo in January that China would never agree to any arrangement that compromises its sovereignty, security or development interests.

Such remarks reflect a "more visceral nationalism in China" to which Xi is responding astutely, said Kerry Brown, a former diplomat and an expert on Chinese politics at the University of Sydney.

"What one sees in him is this sort of immense sense of destiny, he must defend the party's interests as an inheritance for him personally," Brown said. "I think we underestimate that at our peril."

Xi's authority and sense of mission derive partly from the close relationship he enjoys with the military as a result of his father's service as a respected general and Xi's own brief time in uniform while an aide-de-camp to the defence minister three decades ago.

Since November, Xi has paid numerous visits to military units, bolstering his image among the troops while advertising China's growing capabilities.

"Xi is well positioned already given the state of the country as a whole, and especially his support from the military," said Sun, who says Xi began building that backing by moving trusted generals into top positions even before taking over as party chief in November.

A more difficult challenge for Xi will be overcoming China's image problem as a violator of human rights at home and a supporter of repressive regimes abroad.

Despite huge spending on media and other "soft power" strategies, global public opinion surveys published by the Pew Research Center and the BBC show impressions of China are mostly poor or mixed and have generally deteriorated in recent years.