What is Nato and which countries are in it?

Nato Secretary General Mark Rutte has condemned "Russia's reckless behaviour", after a drone crashed into a Romanian apartment building, injuring two people. According to Romania's foreign ministry, the incident happened while Russia was carrying out attacks on Ukraine. Rutte said Nato, of which Romania is a member, "stands ready to defend every inch of allied territory". The 32-member alliance has faced internal pressure from the US in recent months, with President Trump accusing other nations of relying too much on the strength of its military. Nato - the North Atlantic Treaty Organization - was formed in Washington DC in 1949 by 12 countries. The founding members were Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the UK and the US. Nato's main purpose was to block expansion in Europe by the Soviet Union - a group of communist republics dominated by Russia which was dissolved in 1991. It also aimed to prevent the revival of nationalist militarism in Europe and encourage European political integration. The alliance does not have its own army, but member states can take collective military action in response to international crises