WASHINGTON—Afghanistan’s military “will certainly collapse” without some continued American support once all U.S. troops are withdrawn, the top U.S. general for the Middle East told Congress Thursday. Gen. Frank McKenzie also said he was very concerned about the Afghan government’s ability to protect the U.S. Embassy in Kabul. McKenzie, head of U.S. Central Command, said that as the United States pulls out all forces, “my concern is the Afghans’ ability to hold ground” and whether they will able to continue to maintain and fly their aircraft without U.S. aid and financial support. Later, at a Pentagon news conference, McKenzie said the United States will look for “some remote, televised way” to help the Afghan security forces perform maintenance on their aircraft without having U.S. personnel in the country. “We’re certainly going to try to do everything we can from distant locations to assist the Afghans as they maintain the aircraft …