A tiny army is fighting for 20 million lives. Can Mali's military grow fast enough?

BAMAKO, Mali — At the heart of the world's fastest-growing Islamist insurgency, a national force of approximately 12,000 soldiers struggles to defend a population of 20 million. Malian troops are rapidly losing ground, officials in this West African nation say, as militants linked to al-Qaida and the Islamic State sweep the rural north and push toward bigger cities. Leaders pledged this year to nearly double the size of the army, asserting that military help from France and regional partners was not enough to stop the enemy. Yet they are short on weapons, vehicles and basic supplies for combatants already on the payroll — a cost that devours nearly a quarter of Mali's budget. "We don't...