HONG KONG/BEIJING (Reuters) - When Chinese naval supply vessel Qiandaohu entered Australia's Albany Port this month to replenish Chinese warships helping search for a missing Malaysian airliner, it highlighted a strategic headache for Beijing - its lack of offshore bases and friendly ports to call on.
China's deployment for the search - 18 warships, smaller coastguard vessels, a civilian cargo ship and an Antarctic icebreaker - has stretched the supply lines and logistics of its rapidly expanding navy, Chinese analysts and regional military attaches say.
China's naval planners know they will have to fill this strategic gap to meet Beijing's desire for a fully operational blue-water navy by 2050 - especially if access around Southeast Asia or beyond is needed in times of tension.
China is determined to eventually challenge Washington's traditional naval dominance across the Asia Pacific and is keen to be able to protect its own strategic interests across the Indian Ocean and Middle East.
"As China's military presence and projection increases, it will want to have these kind of (port) arrangements in place, just as the U.S. does," said Ian Storey, a regional security expert at Singapore's Institute of South East Asian Studies.
"I am a bit surprised that there is no sign that they even started discussions about long-term access. If visits happen now they happen on an ad-hoc commercial basis. It is a glaring hole."
The United States, by contrast, has built up an extensive network of full bases - Japan, Guam and Diego Garcia - buttressed by formal security alliances and access and repair agreements with friendly countries, including strategic ports in Singapore and Malaysia.
While China is building up its fortified holdings on islands and reefs in the disputed South China Sea, its most significant southernmost base remains on Hainan Island, still some 3,000 nautical miles away from where Chinese warships have been searching for missing Malaysia airlines flight MH370.
Military attaches say foreign port access is relatively easy to arrange during peace-time humanitarian efforts - such as the search for MH370 or during anti-piracy patrols off the Horn of Africa - but moments of tension or conflict are another matter.
"If there was real tension and the risk of conflict between China and a U.S. ally in East Asia, then it is hard to imagine Chinese warships being allowed to enter Australian ports for re-supply," said one Beijing-based analyst who watches China's naval build-up.
"The Chinese know this lack of guaranteed port access is something they are going to have to broach at some point down the track," he said. "As the navy grows, this is going to be a potential strategic dilemma."
Zha Daojiong, an international relations professor at Beijing's Peking University, said the Indian Ocean search was an "exceptional" circumstance and that Chinese strategists knew they could not automatically rely on getting into the ports of U.S. allies if strategic tensions soared.
China's navy had significantly expanded friendship visits to ports from Asia and the Pacific to the Middle East and Mediterranean in recent years, but discussions over longer-term strategic access were still some way off, he said.
"At some point, we will have to create a kind of road-map to create these kind of agreements, that is for sure, but that will be for the future," Zha said.
"We are pragmatic and we know there are sensitivities surrounding these kinds of discussions, or even historic suspicions in some places, so the time is probably not right just yet," he said.
"I expect to see more friendship visits, and on-going access on a request basis. Then there is the issue of making sure the facilities can meet our needs."
Operationally, long-range deployments such as the anti-piracy patrols and the search for wreckage of MH370 have proved important logistical learning curves, he added.
Potential blue-water deployments of future air-craft carrier strike groups further complicates China's logistical outlook.
China's first carrier, the Liaoning, a Soviet-era ship bought from Ukraine in 1998 and re-built in a Chinese shipyard, is being used for training and is not yet fully operational.
Regional military attaches and analysts said it could be decades before China was able to compete with U.S. carriers, if at all.
Tai Ming Cheung, director of the U.C. Institute of Global Conflict and Co-operation at the University of California, described the MH370 search as a "major learning moment" for the People's Liberation Army (PLA) and could lead to a push from its top brass to develop global power-projection capabilities.
The PLA covers all arms of the military, including the navy.
Chinese officials and analysts have bristled at suggestions by Western and Indian counterparts that Beijing is attempting to create a so-called "string of pearls" by funding port developments across the Indian Ocean, including Pakistan, Sri Lanka, Bangladesh and Myanmar.
Chinese analysts say the ports will never develop into Chinese bases and even long-term access deals would be highly questionable, given the political uncertainties and the immense strategic trust this would require.
Storey, of Singapore's Institute of South East Asian Studies, said the "string of pearls" theory was increasingly seen as discredited among strategic analysts.
So far this decade, Chinese naval ships have visited Gulf ports and other strategic points across the Middle East, including Oman, Israel, Qatar and Kuwait, after completing piracy patrols.
But despite its rapid naval build-up, many experts believe China is a decade or more away from being able to secure key offshore shipping lanes and was still reliant on the United States to secure oil choke-points such as the Straits of Hormuz that leads to the Gulf.
Closer to home, the disputed South China Sea offers few solutions. China's eight fortified holdings on reefs and islets across the contested Spratly archipelago are not considered big enough for a significant offshore base, according to Richard Bitzinger, a regional military analyst at Singapore's S. Rajaratnam School of International Studies.
Nor is the base at Woody Island in the Paracels further north, where China is expanding a runway and harbour.
"Beyond the PLA's significant naval bases on Hainan Island, I just can't see where the Chinese will be able to get the port access they will need in Southeast Asia over the longer term," Bitzinger said. "The intensifying disputes with the likes of the Philippines and Vietnam have hardly helped."
The Philippines and Vietnam, along with Malaysia and Brunei, dispute China's claim to much of the South China Sea, one of the world's most important trade routes. Taiwan's claim mirrors that of Beijing.
Vietnam, the Philippines, Malaysia and Taiwan all maintain military bases across the Spratlys, which sit above a seabed rich in oil and gas potential.
"The U.S. Navy has been at this for 100 years or so," and constantly works at maintaining and nurturing its strategic network, Bitzinger said. "China's being doing it for about 15 ... China's not going to be able to catch up overnight."
(Additional reporting by Grace Li in Hong Kong and Matt Siegel in Sydney. Editing by Dean Yates and Mark Bendeich)