Why does Turkey not want to send army against Islamic State?

Turkey has rejected pressure from Nato allies for it to send its army across the border into Syria, although its parliament authorised military action last week. The country has strong reasons for being reluctant to intervene.

The Turkish government says it is unwilling to take part unless the coalition targets the regime of Syrian President Assad and sets up a no-fly zone.

The BBC's security correspondent, Frank Gardner, reports.