Turkish MPs have voted to allow its military to enter Iraq and Syria and foreign troops to use its territory to combat the threat of the Islamic State.
The motion was passed with 298 MPs in favour and 98 against.
Turkey has been unwilling to take on the Islamic State (IS) up until now because militants had been holding 46 Turkish hostages, but they were released last month.
In voting in support of combating IS, Turkey has opened itself up to retaliatory attacks by the militants that hold territory along its vast 560 mile porous border with Syria.
Turkey has long been accused of helping the Islamic State and other Islamist groups in the Syrian Civil War, and permitted the flow of international jihadis into Syria over its border. Istanbul has always denied these claims.
Independent Turkish businessmen have also been accused of aiding the flow of oil from IS-controlled oil fields onto the black market, a major source of IS revenues.
The decision comes as IS fighters continue to besiege the Kurdish town of Kobane on the Syria-Turkey border, from where 150,000 refugees have fled across the border into Turkey.