CAIRO (Reuters) - Al Qaeda leader Ayman al-Zawahri called on young Muslim men in the United States and other Western countries to carry out attacks inside there and urged greater unity between militants.

"I call on all Muslims who can harm the countries of the crusader coalition not to hesitate. We must now focus on moving the war to the heart of the homes and cities of the crusader West and specifically America," he said in an audio recording posted online on Sunday, referring to nations making up the Western-led coalition in Iraq and Syria.