China began sea trials on Wednesday for its first aircraft carrier, a ship that has come to symbolize the nation’s growing military and maritime ambitions.

The retrofitted former Soviet ship, called the Varyag, has long been considered the first step in China’s plan to eventually build a handful of carriers as part of a wider development of naval might.

On the same day China’s carrier set sail, Taiwan brandished its most advanced missile at the Taipei Aerospace and Defense Technology Exhibition. The display was accompanied by a billboard calling the missile, Hsiung Feng III, an “aircraft carrier killer.” An image of it appeared alongside a picture of a craft closely resembling the Varyag crippled and aflame.

Others in the region have been watching China’s rapidly modernizing and growing military amid disputes over territorial claims. Six countries claim portions of the South China Sea, which is believed to hold valuable oil and minerals, but China’s claim is by far the broadest, encompassing almost the entire region.

The carrier serves as a signal of sorts to other nations, said Dean Cheng, a research fellow at the Heritage Foundation. “This will start affecting things like South China Sea negotiations, not because of an overt change in military balance, but it will be looming, brooding in the background.”

China bought the carrier from Ukraine in 1998 with the intent of turning it into a floating casino. But for roughly the past decade, it has undergone retrofitting in the northeastern port of Dalian.

A new engine and radar equipment were added, and the carrier retains its original runway to launch fighters. Both Chinese and foreign military analysts think China is years away from developing a fully operational carrier group, including the capability to launch and land fighter jets from the ships.

China’s state-run Xinhua News Agency said Wednesday that the sea trials “will be a lengthy process from the sea test to the shaping of combat prowess.” It added that the carrier “is only a platform for scientific research, experiments and training.”

China is the only one of the five permanent members of the U.N. Security Council without an operational carrier.

Staff writer Keith B. Richburg in Shanghai contributed to this report.