NATO Secretary General Jens Stoltenberg steps down on Tuesday after 10 testing years for the Western military alliance's unity and purpose. Stoltenberg will hand over to former Dutch prime minister Mark Rutte with a wreath-laying ceremony and an official handshake at NATO headquarters in Brussels.

Jens Stoltenberg is leaving NATO in early October. The Secretary General of the North Atlantic Treaty Organization can use his many years of experience in his new position, which is also related to international security.

BRUSSELS (AP) — One of NATO’s longest serving top officials, Secretary-General Jens Stoltenberg, steps down on Tuesday and will hand over the reins to former Dutch Prime Minister Mark Rutte, as the military alliance confronts some of the biggest challenges in its history.