NATO chief Jens Stoltenberg and UN Secretary-General António Guterres have welcomed ongoing cooperation between the two international organisatons. 

AVA- At a meeting on the sidelines of the UN General Assembly in New York, they also exchanged views on the Western Balkans and the security situation in Afghanistan.
Over the past decade, the two organisations have stepped up cooperation, working closely to support Afghanistan and Iraq, according to a statement from the alliance.
Stoltenberg is scheduled to deliver a speech on NATO’s role in the fight against terrorism at the National September 11 Memorial and Museum.
Following 9/11, NATO invoked its collective defence clause – Article 5 of the Washington Treaty – for the first time in support of the United States.
This led to the Alliance's biggest ever operation in Afghanistan. In 2015, NATO received a piece of twisted steel from the Twin Towers, which is displayed at the Alliance’s new headquarters in Brussels.