The United States has called on China to give more information about its first aircraft carrier, which was sent out on an initial sea trial Wednesday.

A spokeswoman for the U.S. State Department told reporters that Washington would welcome any kind of explanation China would like to give for needing this kind of equipment. She said China's lack of transparency about its military acquisitions and its military budget raises concerns.

Earlier Wednesday, Beijing announced that the carrier it purchased from Ukraine in 1998 had left the port of Dalian for its inaugural sea trial.

Little was said about the vessel formerly known as the Varyag until last month when Chinese defense officials sad it would be used for scientific research, experiments and training.

But reports that China is planning to build at least three more carriers are worrying its neighbors, especially those whose territorial claims in the East and South China seas conflict with China's.

In an apparent response, Taiwan displayed a model anti-ship cruise missile Wednesday at an exhibition of aerospace and defense technology in Taipei. The Taipei Times newspaper said the model Hsiung Feng-3 missile was shown against a large picture of a burning aircraft carrier that resembles the refitted Varyag.

The stripped-down hull of the Varyag was purchased from Ukraine, which inherited it from the Soviet Union after the communist state collapsed in 1991.

China's defense ministry said the carrier will return from its maiden voyage shortly for further construction work. It also said the process of training pilots how to fly planes off an aircraft carrier is “in progress.”

Officials say China is committed to a naval strategy of defending its own shores and that the carrier poses no threat to any other country. Beijing also has pointed out that China is the only one of the five permanent member of the United Nations Security Council without an operational aircraft carrier.