TAIPEI—Taiwan’s defence ministry said on Tuesday it will boost training of its reserve forces next year, including doubling down combat and shooting exercises, as China increased military activities near the island. Beijing has not ruled out taking the island by force. Tensions between Taiwan and China, which claims the democratic island as sovereign territory, have escalated in recent weeks as Beijing raises military pressure that included repeated missions by Chinese warplanes in Taiwan’s air defence identification zone. Defence Minister Chiu Kuo-cheng last month described the situation as “the most serious” in more than 40 years and urged extra military spending for domestically-made weapons. Starting next year, mandatory refresher training for some reserve forces will be increased to 14 days, from the current five to seven days, to “effectively elevate combat capability of the reserve forces,” the defence ministry said in a statement. Those reservists will be required to more than …