China formally entered its first aircraft carrier into service on Tuesday, underscoring its ambitions to be a leading Asian naval power, although the ship is not expected to carry a full complement of planes or be ready for combat for some time.

The Defense Ministry's announcement had been long expected and was not directly linked to current tensions with Japan over a disputed group of uninhabited islands in the East China Sea.

In a brief notice on its website, the ministry said the carrier's commissioning significantly boosted the navy's combat capabilities and its ability to cooperate in responding to natural disasters and other non-traditional threats.

"It has important significance in effectively safeguarding national sovereignty, security, and development benefits, and advancing world peace and common development," the statement said.

China had partly justified the launching of a carrier by pointing out that it alone among the five permanent United Nations Security Council members had no such craft. That had been particularly glaring given the constant presence in Asia of carriers operated by the U.S. Navy, which maintains 11 worldwide.

President Hu Jintao, also chairman of the commission that controls the military, presided over a ceremony Tuesday morning at the ship's home port of Dalian, along with Premier Wen Jiabao and top generals. Hu "fully affirmed" the efforts of those working on the ship and called on them to complete all remaining tasks according to the highest standard, the Defense Ministry said.

The carrier is the former Soviet navy's unfinished Varyag, which was towed from Ukraine in 1998 minus its engines, weaponry and navigation systems. Christened the Liaoning after the northeastern province surrounding Dalian, the ship began sea trials in August 2011 following years of refurbishment.

So far the trial runs of the aircraft carrier have been to test the ship's propulsion, communications and navigation systems. But launching and recovering fixed-wing aircraft at sea is a much trickier proposition. It will take years to build the proper aircraft, to train pilots to land in adverse weather on a moving deck, and to develop a proper carrier battle group.

China is developing a carrier-based fighter-bomber, the J-15, derived from Russia's Sukhoi Su-33, along with a prototype stealth carrier fighter, the J-31.

Beijing hasn't said what role it intends the carrier to fill other than helping safeguard China's coastline and sea links. The Liaoning has also been portrayed as a kind of test platform for the future development of up to five domestically built Chinese carriers.

Writing in Tuesday's China Daily newspaper, retired Rear Adm. Yang Yi said the carrier will be used to master the technology for more advanced carriers. He said it also will be used to train in how to operate such a craft in a battle group and with vessels from other nation's navies.

Without specifically mentioning China's territorial disputes, Yang acknowledged other countries' concerns about its growing military might, but said Beijing wouldn't shy from flexing its muscles.

"When China has a more balanced and powerful navy, the regional situation will be more stable as various forces that threaten regional peace will no longer dare to act rashly," Yang wrote.

Whatever its practical effects on China's global status, the carrier embodies huge symbolism for China's political and military leaders as a totem of their country's rise from weakness to strength, according to Andrew S. Erickson, a China naval specialist at the U.S. Naval War College.

"While (Chinese navy) acceptance of this `starter carrier' is the first step in a long journey, it is a journey that will take place in full view of the world, and one that will ultimately take Beijing to a new place as a great sea power," Erickson wrote on his blog.

The carrier's political importance was highlighted in Wen's remarks to the ceremony, in which he said it would "arouse national pride and patriotic passion."

"This has mighty and deep significance for the opening of a new facet in our enterprise of socialism with Chinese characteristics," he said.