Islamic State (IS, formerly ISIS) fighters facing defeat in Syria are slipping across the border into Iraq, US and Iraqi officials say. Likely more than 1,000 IS fighters have crossed the open, desert border in the past six months, defying a massive operation by US, Kurdish, and allied forces against the remnants of the jihadist group in eastern Syria, AP reported, citing three Iraqi intelligence officials and a US military official. They say cells operating in four northern provinces are carrying out kidnappings, assassinations, and roadside ambushes aimed at intimidating locals and restoring the extortion rackets that financed the group’s rise to power six years ago. The militants can count between 5,000 and 7,000 among their ranks in Iraq, where they are hiding out in the rugged terrain of remote areas, according to security sources.