TAIPEI (Reuters) -China spent $21 billion on military exercises in the Taiwan Strait, the East and South China Sea and the Western Pacific last year, nearly 40% higher than 2023, according to Taiwan government estimates based on its tracking of aircraft and ships and working out the cost of fuel and other expenses. The internal research by Taiwan's armed forces, reviewed by Reuters and corroborated by four Taiwan officials, offers rare detail of where China's defence spending is probably going as Beijing expands its military footprint and scope of its drills, alarming regional capitals and Washington.