The Netherlands is a founding member of NATO and a partner in the Benelux Union
Background
NATO records the Netherlands among the twelve countries that signed the North Atlantic Treaty in Washington on 4 April 1949. The other founding members were Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, Norway, Portugal, the United Kingdom and the United States. The Netherlands is also one of the three partners of the Benelux Union with Belgium and Luxembourg. The grouping began as the Benelux Economic Union under a treaty signed in 1958 for an initial period of fifty years. A revised treaty signed in The Hague on 17 June 2008 renamed it the Benelux Union and entered into force on 1 January 2012. The Benelux Secretariat-General is in Brussels.
In plain words
NATO North Atlantic Treaty Organization — A military alliance created by the North Atlantic Treaty of 1949.