Mauritanian President Mohamed Ould Abdel Aziz, who has opposed sending troops to combat Islamists in northern Mali, said Monday he would not rule out contributing to a UN force if the situation improves. "If the situation changes... there will be nothing preventing Mauritania, as a UN member, from sending troops to the north (of Mali) or in the country's western regions to provide stability and security," he said at a press conference. "We will take on this responsibility as soon as possible," he said, speaking at a joint event with his Niger counterpart Mahamadou Issoufou.