Terror prevention

What prevents Russia, US from fighting against Islamic State together?

Russia’s arch foe these days is the Islamic State. Washington claims that the worst threat to world peace is what it invariably refers to as Russia’s ‘aggression’ in Europe and operations by terrorists in Syria and the United States itself. Both countries have had and still have different priorities all along, Russian experts say. As for the struggle against radical Islamism, the United States’ attitude has always been rather dubious.