A timeline: Syrian-Turkish relations

Turkey is being dragged further into the four-year conflict in neighbouring Syria following a deadly suicide attack, blamed on the Islamic State group, that killed 32 activists near the border.

A former ally of Syria, Turkey broke off relations with President Bashar al-Assad in 2011 and has accepted almost two million Syrian refugees since then.

Following are key dates in the relations between Ankara and Damascus:

- 2011 -
- September 13: "The Syrian people do not believe al-Assad, I do not either," says Recep Tayyip Erdogan, then premier, a few months after calling the Syrian leader his "friend". Erdogan warns of civil war in Syria. "I fear that matters will end with a civil war breaking out between the Alawites and the Sunnis," he says in reference to Assad's Shia Alawite sect, and the majority Sunni Muslims.

- October 2: Following a series of meetings in several Turkish cities, Syrian opposition leaders announce the creation of the Syrian National Council (SNC), which groups political factions opposed to the Assad regime.

- November 15: Turkey passes its first sanctions against Syria, and halts joint oil exploration with the country.

- 2012 -

- June 22: A Turkish plane that Ankara says was on a training mission in international airspace is shot down by Syrian forces.
Turkey deploys anti-aircraft missiles along the border with Syria, and in 2013 receives Patriot anti-missile batteries as part of a NATO agreement.

- 2013 -

May 11: Twin attacks kill 52 people in Reyhanli, a large Turkish town near the border with Syria.

A Turkish investigation points to involvement by Syrian intelligence services, but Damascus formally denies any role in the attacks.

- 2014 -

September 16: IS militants attack the Syrian border town of Kobane, and seize parts of it. Kobane becomes the scene of fierce battles.
Under international pressure, Turkey allows armed Kurdish Peshmerga fighters to transit its territory to join the fighting in Kobane. Ankara fears bolstering the Kurdistan Workers Party (PKK), which has fought a decades-long insurgency to create an autonomous Kurdish zone inside Turkey.

- 2015 -

May 16: Turkey says it has shot down a Syrian helicopter that violated its airspace.

Turkish forces had already downed a Syrian jet accused of entering Turkish airspace in March 2014, and a year earlier Turkish jets shot down another Syrian helicopter.

July 20: At least 32 people die when a suspected IS suicide bomber attacks a gathering of activists in the town of Suruc, near the Syrian/Turkish border.