Syrian–Turkish border clashes during the Syrian Civil War

Numerous incidents along the Syrian–Turkish border have taken place during the Syrian Civil War, straining the relations between the countries. Dozens were killed, both among civilians and military personnel. Following Syria's downing of a Turkish jet  in 2012, Turkish Prime Minister Recep Tayyip Erdoğan changed the military's rules of engagement so that any Syrian element approaching the border would be deemed a threat and be treated as a military target. Turkey has bolstered its defenses and deployed additional troops on its border with Syria in mid to late September 2013, with convoys of military vehicles ferrying equipment and personnel and additional short range air defenses set up.

December 2011 incidents
During the 5 December 2011 night, about 35 armed fighters tried to cross the border of Syria from Turkey, but were engaged immediately by the Syrian border forces who inflicted several wounds to them and were able to repel them back to Turkey. Once they were back on Turkish soil, the Turkish army allegedly picked them up in trucks and took care of the injured fighters. A further attempt happened during the night of 12 December, when 15 infiltrators tried again to cross the border. They were unsuccessful and two of them were killed by Syrian border patrols.

F4 jet incident
On 22 June 2012, Syrian air defenses shot down a Turkish F-4 Phantom fighter jet, and both pilots were killed. The incident significantly raised tensions between the two countries. Syria stated that it had shot the fighter down using anti-aircraft artillery near the village of Om al-Tuyour, while it was flying over Syrian territorial waters one kilometer away from land. Turkey's foreign minister stated the jet was shot down in international airspace after accidentally entering Syrian airspace, while it was on a training flight to test Turkey's radar capabilities. Turkish Prime Minister Recep Tayyip Erdoğan vowed retaliation, saying: "The rules of engagement of the Turkish Armed Forces have changed ... Turkey will support Syrian people in every way until they get rid of the bloody dictator and his gang." Ankara acknowledged that the jet had flown over Syria for a short time, but they said such temporary overflights were common, had not led to an attack before, and alleged that Syrian helicopters had violated Turkish airspace five times without being attacked and that a second, search-and-rescue jet had been fired at. Assad later expressed regret over the incident. In August 2012, reports appeared in some Turkish newspapers claiming that the Turkish General Staff had deliberately misinformed the Turkish government about the fighter's location when it was shot down. The reports said that a NATO command post at Izmir and a British base in Cyprus had confirmed that the fighter was shot down inside Syrian waters and that radar intelligence from U.S. forces had disproved any "accidentally entered Syrian waters" flightpath error. The General Staff denied the claims.

October 2012 cross-border clashes
Tensions were further raised later that year when Syrian mortar rounds began landing in Turkish territory. On 3 October, a Syrian mortar shell hit the Turkish town of Akçakale, killing 5 civilians. Turkey responded by shelling Syrian army positions along the border. Throughout October, Syrian mortar shells repeatedly landed in Turkish territory, and the Turkish military launched retaliatory artillery and mortar strikes, firing into Syria a total of 87 times. These attacks reportedly killed 12 Syrian soldiers and destroyed several tanks.

January 2013 incident
In the early hours of 14 January 2013, a shell fired by unknown Syrian forces landed in an olive grove near the border village of Akçabağlar, causing no casualties. On January 30, Syrian El Muhaberat agents tried to cross the border between Turkey and Syria but were turned back under fire by Turkish forces.

February 2013 bombing
On 11 February 2013, a bomb exploded at the Turkısh-Syrian border crossing in Cilvegözü, killing 14. According to BBC, the deadly attack killed 17 people and injured 30 more.

April 2013 border air raid
On April 30, 2013, according to Syrian opposition activists, the Syrian air force raided the headquarters of a rebel camp on Syrian-Turkish border, killing 5. Activists told Hurriyet Daily News that the air attack was made on headquarters of a Salafist group Ahrar al-Sham. A Turkish aid worker said the air strike also hit a warehouse on the Syrian side of the border used by aid groups. Another Syrian activist at Bab al-Hawa said people waiting to cross the Syrian-Turkish border were among those hit. He added that at least 15 wounded were taken to hospital near the crossing on the Syrian side and among the dead were a one-and-a-half-year-old child and two teenage girls. Some Syrian activists said some of the casualties were suffering breathing difficulties but said they did not know what type of munitions had been used in the attack. "We cannot confirm that there were any chemical weapons involved," Reyhanli mayor Huseyin Sanverdi told Reuters.

May 2013 Akcakale incident
On 2 May 2013, fighting occurred between Syrian anti-government insurgents and Turkish border guards at the Akcakale border crossing. One Turkish border guard was killed in the engagement, reportedly the first armed clashes between Turkish government agents and anti-Assad militants.

May 2013 Reyhanli bombing
On 11 May 2013, two car bombs exploded in the town of Reyhanlı, Hatay Province, Turkey. At least 51 people were killed and 140 injured in the attack. The attack was the deadliest single act of terrorism to occur on Turkish soil.

In response to the attacks, the Turkish government sent large numbers of air and ground forces to increase the already heavy military presence in the area.

By 12 May 2013, nine Turkish citizens, alleged to have links to the Syrian intelligence agency, had been detained. On 21 May 2013, the Turkish authorities charged the prime suspect, the state-run Anatolia news agency reported. Four other suspects were also charged. 12 people had been charged in total. All suspects were Turkish nationals that Ankara believes were backed by the Syrian government.

On 30 September 2013, some websites claimed that the Islamic State of Iraq and the Levant (ISIL), the al-Qaeda group operating in Iraq and Syria, accepted responsibility for the attack, threatening further attacks against Turkey.

2013 helicopter incident
On September 16 2013, Turkish jets shot down a Syrian helicopter on the Syrian-Turkish border. According to Turkish official statement, Turkish warplanes made the intercept after a Syrian Mi-17 helicopter had crossed into Turkish airspace and the government warned it had taken all necessary measures to defend itself against any further such violations. Syrian army acknowledged the helicopter had strayed into Turkish airspace for a short time, while monitoring "terrorists" moving across the border into Syria, but said it was an accident and that the aircraft was on its way back when it was shot down.

January 2014 incident on Syrian Kurdistan border
Five Syrian Kurds killed while crossing borders into Turkey on January 20, 2014. Zahir Mulla and Muhammad Ahmad were killed along with other three men (whose identities couldn't be identified), when Turkish border guards opened fire. Others, who accompanied the victims, were hardly beaten by the Turkish guards.

January 2014 Turkish airstrike
On 28 January 2014, the Turkish air force performed an airstrike on Syrian territory, allegedly aiming to hit ISIS convoy inside Syria. According to Turkish General staff, a pickup, a truck and a bus in an ISIL convoy were destroyed”. Turkish officials also said the January 28 attack was meant to retaliate for ISIL fire on the Turkish Army along the Syrian border. They also cited ISIL raids on ethnic Turkish communities in northern Syria, which sparked an exodus of thousands to Turkey. The Turkish attack came amid threats by ISIL to expand operations into Turkey - a NATO state.

March 2014 Turkish shootdown of a Syrian aircraft
On 23 March 2014, Turkish fighter jets shot down a Syrian warplane. The Syrian Arab Republic claims that its aircraft was in Syrian airspace on a mission to attack rebel held areas in the city of Latakia when it was shot down by Turkey in an act of "blatant aggression." The Syrian pilot successfully ejected from the aircraft as the aircraft was being shot down. Turkish Prime Minister Erdoğan stated that Turkish F-16s shot down the aircraft for violating Turkish airspace and said that the Turkish "response will be heavy if you violate our airspace."

The Refugee problem, blowback and the battle of Kobanē
In the Summer of 2014, there were riots in Istanbul over relations with locals and refugee, and along the border with Syria as during the September battles with ISIS the army refused to let any more enter the country before relenting.

This has led to a revival of planning for a Turkish buffer zone on the Syrian side of the border to house the refugees.

Around Sept. 20th, the so-called Islamic State launched an offensive to try to capture the border town of Kobanē besieging it from three sides. More than 140,000 Kurds have fled the town and surrounding villages, crossing into Turkey and leading to protests and riots on the Turkish side. and the ending of the two year old cease fire between Turkey and the PKK

ISIS appeared to have taken control of a hill from where fighters from the YPG, the main Kurdish armed group in northern Syria, had been attacking them, 10 km (6 miles) west of Kobanē. The fighting has gotten so close to the border that errant shells have landed in Turkish territory.

On September 29, M60A3 tanks of the Turkish Land Forces were moved to the Syrian border as a show of force to deter any hostile incursions by ISIS forces.

Reactions

 * Syria - In a statement carried by Syrian state news agency SANA, on September 2013, following a helicopter incident on the Turkish border, it accused Prime Minister Tayyip Erdogan's government of trying to increase tensions between the two countries.
 * 🇹🇷 Turkey - Following the September 2013 helicopter incident on Turkish-Syrian border Turkish Foreign Minister Ahmet Davutoglu told reporters in Paris that "Turkey will definitely not allow any violation of its borders ... We will defend our borders and our people's security to the end".