The People’s Liberation Army’s most advanced aircraft carrier, the Fujian Type 003, transited the Taiwan Strait on Tuesday, a day after Taipei launched a combat readiness exercise.

Song Zhongping, a military commentator and former PLA instructor, said the Fujian could be heading back to its home port in the southern island province of Hainan for a break before it headed out to the South China Sea for more training.

Taiwan’s armed forces closely monitored the vessel throughout its passage using joint intelligence, surveillance and reconnaissance assets and maintained full awareness of its movements, the island’s defence ministry said on Tuesday.

The ministry released a photo showing the Fujian with an empty deck. Previously, Song said a lack of visible aircraft could suggest the carrier was operating in a low-threat state.

The transit came a day after Taiwan kicked off a five-day military drill called the Immediate Combat Readiness Exercise, an effort meant to boost the island’s ability to quickly move to a wartime footing.

The exercise would focus on the period immediately before a conflict began, testing whether units could quickly prepare and deploy after receiving orders, Taiwanese defence officials said.