DUSHANBE—Afghanistan’s northern neighbour Tajikistan held its largest ever military exercise on Thursday involving the Central Asian nation’s entire army, and President Emomali Rakhmon urged vigilance amid fighting to the south of the border. Insecurity has been growing in Afghanistan in recent weeks, largely spurred by fighting in its provinces as U.S.-led foreign troops complete their withdrawal and the Taliban launch major offensives, taking districts and border crossings. Tajikistan mobilised 130,000 men from its military reserve in addition to 100,000 active servicemen for the three-hour exercise on Thursday, Rakhmon said at a military parade. More than 1,000 military vehicles, hundreds of artillery guns and mortars and dozens of aircraft including helicopters were deployed during the exercise, Rakhmon’s office said in a statement. “Due to the unstable situation in the region I once again remind the people of Tajikistan that we must be ready to protect the peace and stability that have …