NATO has helped provide security in Afghanistan for nearly 20 years, but the country's government and military are strong enough to provide security without the support of international forces, Alliance Secretary General Jens Stoltenberg told AP.

NATO assumed responsibility for security in Afghanistan in 2003, two years after the US-led coalition toppled the Taliban. There are now fewer than 9,000 foreign troops in the country who must leave by September 11 at the latest.

“I think that the Afghans, they also realize that we have been there now for 20 years and we have invested heavily in blood and treasure in Afghanistan,” NATO Secretary-General Jens Stoltenberg told The Associated Press, aboard a U.K. aircraft carrier involved in wargames off the coast of Portugal.

“Afghanistan has come a long way, both when it comes to building strong, capable security forces, but also when it comes to social and economic progress. At some stage, it has to be the Afghans that take full responsibility for peace and stability in their own country,” Stoltenberg said in an interview.