China says its first aircraft carrier has formally entered service.
The Chinese ministry of defence says the carrier will increase China's capacity to defend the interests of state sovereignty.
The 300 metre Liaoning - named after the province where it was refitted - is a refurbished Soviet ship purchased from Ukraine.
For now the carrier has no operational aircraft and will be used for training.
But China says the vessel, which has undergone extensive sea trials, will increase its capacity to defend state interests, the BBC reports.
The Liaoning was formally handed over to the navy at a ceremony attended by top Chinese leaders at Dalian Port, state-run Xinhua news agency says.
The official commissioning of the country's first aircraft carrier signals China's status as a rising power, says the BBC's correspondent in Beijing.
It comes at a time when Japan and other countries in the region have expressed concern at China's growing naval strength.
China and Japan are embroiled in a row over disputed islands in the East China Sea.
Several South East Asian nations are also at odds with China over overlapping territorial claims in the South China Sea.
It also comes weeks ahead of a party congress expected to see the transition of power to a new generation of Chinese leaders.