On that day in August, amid pouring rain that had hampered police officers’ use of tear gas, Ivan was heading back to the van his protest cell was using to transport supplies. It was only a couple of blocks away, but as he jogged over, he turned onto a side street and suddenly found himself facing a new line of protesters that had splintered off from the main group. Looking behind, he saw a corresponding line of heavily-armed riot police, with a red warning banner held up over their heads.