At the heart of NATO, the world’s longest-standing security alliance, is the notion that an attack on one is an attack on all. But with many in Europe doubting a Trump-led United States will really come through for them,

President Macron has aired the idea that France's deterrence force could be used to defend of other European countries.

In a televised address, President Emmanuel Macron warned that Europe needed to deal with a retreating America and a bellicose Russia.