Why has Belfast erupted in anti-immigrant violence after a knife attack?

Violent protests have broken out in Belfast, Northern Ireland, after a knife attack allegedly perpetrated by a Sudanese refugee. Hundreds of masked protesters blocked roads, torched cars and buildings, and residents were evacuated. The suspect, a 30-year-old Sudanese refugee with a valid residence permit, was charged with attempted murder and other crimes. The incident has sparked tensions across Britain, with some accusing the asylum policy of allowing dangerous men into the country.