No matter how hard he tries, Nemer, a 22-year-old Syrian immigrant living in New Jersey, cannot shake the vision from his mind: 60 people huddled in a tin cell made for 10 out in the Syrian desert. They take it in turns to sleep on the floor. At night the desert is so cold the metal is like ice; by morning the prison is an oven.

This was the fate of a friend jailed for 18 months for publishing an anti-regime poem on Facebook. ‘Like this they torture you for 24 hours,’ says Nemer (who is using a pseudonym out of concern for his family’s safety). ‘But when a friend calls me to say, “Just forget about Syria, forget about going back,” it’s like pulling one of my nerves. It’s like holding my heart and taking it out of my body to tell me I’m not going back to Syria.’