Britain's Prime Minister Gordon Brown, US President Barack Obama, NATO Secretary General Jaap de Hoop Scheffer and French President Nicolas Sarkozy (L-R) walk after a minute of silence to honour NATO military personnel for service in operational theatres, in Strasbourg, April 4, 2009. The North Atlantic Treaty Organisation (NATO) military alliance is celebrating its 60th anniversary this week at a summit co-hosted by Germany and France. [Agencies]

US first lady Michelle Obama (L) and France's first lady Carla Bruni-Sarkozy visit Strasbourg Cathedral (Notre-Dame de Strasbourg), April 4, 2009. The North Atlantic Treaty Organisation (NATO) military alliance is celebrating its 60th anniversary this week at a summit co-hosted by Germany and France. [Agencies]

US President Barack Obama speaks during his final news conference after the NATO summit in Strasbourg April 4, 2009. [Agencies]