Crowds of protesters gathered outside the American Embassy in Athens, Greece, on Saturday, burning the flags of the US and the NATO alliance.
Videos purportedly filmed on the scene show the flags on fire, along with groups of people holding banners decrying Greece's membership in the European Union and NATO.
The gathering takes place amid the ongoing meeting of NATO military chiefs in Athens, who are set to discuss "NATO's operations, missions and activities, the alliance's deterrence and defence posture".
The conference is scheduled for 17-19 September, hosting some 30 NATO military chiefs.
Greece has been a member of the North Atlantic Treaty Organisation since February 1952. This year, it also marks 40 years in the European Union, joining the bloc in 1981. Opinions on its membership, however, are diverse, with critics pointing at how the European Commission noted the weak industrial base of the country's economy when Greece joined the EU.