ISIS has lost vast swathes of its territory and the population under its brutal command has drastically declined since its height in 2014. But that has not weakened the extremist group's aims of spreading fear in the name of radical Islam, Mathieu Guidere, a professor of Middle Eastern and Islamic Studies and expert in radicalisation, said. He told Express.co.uk that recent attacks in Paris and Nice have marked a crucial "psychological turning point", demonstrating to ISIS sympathisers in Western cities that an attack was possible without weapons training or logistical support.