Taiwanese President Tsai Ing-wen convened a meeting of top defense officials and urged them Friday to be on a lookout for military developments concerning China following a helicopter crash that killed the island’s top military officer and other prominent personnel. The meeting followed the grounding for inspection of Taiwan’s 52 UH-60M Black Hawk choppers belonging to the air force, the army and the National Airborne Service Corps., the agency responsible for search and rescue operations.