TAIPEI, March 6 (Reuters) - Taiwan Defence Minister Chiu Kuo-cheng warned on Monday the island has to be on alert this year for a "sudden entry" by the Chinese military into areas close to its territory amid rising military tensions across the Taiwan Strait. Chiu said China was looking to "make trouble under a certain pretext", adding that might include visits to the island made by senior foreign government officials or Taiwan's frequent military contacts with other countries. Chiu said since China has abandoned a tacit agreement on military movements in the Strait, Taiwan has made preparations to "fire the first shot" if Chinese entities, including drones or balloons, enter its territorial space