The outgoing Secretary General Jens Stoltenberg appreciated the former Dutch Prime Minister Mark Rutte's experience, his ability to reach compromise in negotiations and his firmness in insisting on values.

Mark Rutte praised the exemplary tenure of his predecessor and added that NATO is today stronger and more united than ever, in large part because of Mr. Stoltenberg’s leadership. He also outlined his three priorities for the Alliance: the first, a strong NATO with an effective and credible defence; the second, step up support to Ukraine; and the third, strengthening partnerships, including NATO's partnership with the EU.

Former Norwegian Prime Minister Jens Stoltenberg leaves the office after 3 654 days filled with historic milestones. He was the second longest serving Secretary General of the Alliance.

What exactly is a NATO Secretary General, how does someone get the job and what do they do every day? Find out here.