The Islamic State group has trained at least 400 fighters to target Europe in deadly waves of attacks, deploying interlocking terror cells like the ones that struck Brussels and Paris with orders to choose the time, place and method for maximum carnage, The Associated Press has learned.

The network of agile and semiautonomous cells shows the reach of the extremist group in Europe even as it loses ground in Syria and Iraq. The officials, including European and Iraqi intelligence officials and a French lawmaker who follows the jihadi networks, described camps in Syria, Iraq and possibly the former Soviet bloc where attackers are trained to attack the West. Before being killed in a police raid, the ringleader of the Nov. 13 Paris attacks claimed to have entered Europe in a multinational group of 90 fighters, who scattered “more or less everywhere.”