K., 28, is on the line from Aleppo. He speaks to Al-Monitor via Skype, with a soundtrack of barrel bombs and gunfire, but that's no news — and not the source of the disappointment and dismay that mark his voice. A trainee doctor turned sniper, he was long one of about 5,000 men that the Islamic State of Iraq and as-Sham (ISIS), the al-Qaeda offspring currently in the spotlight for its stunning gains in Iraq, is estimated to have deployed in Syria.