Signals abound that the fighting in Syria has spilled over into Turkey. On Tuesday night, Turkish police clashed with armed militants from the Islamic State of Iraq and the Levant, the Syrian branch of Al-Qaida. During the clash, three Turkish police officers were wounded, according to local media.

This latest incident follows the death of three people last week, including a soldier and a police officer, in a terrorist attack that was also attributed to the Syrian Al-Qaida branch.

Police and special forces engaged in a comprehensive arrest operation in the Umraniye district of Istanbul overnight. During the operation, suspects opened fire on police, injuring two. Two armed suspects, a man and a woman, were also wounded. Security tensions in Turkey are on the rise as local elections are scheduled for Sunday, which will serve a measure of strength for Prime Minister Recep Tayyip Erdogan’s government.

The suspects responsible for the attack on Thursday were arrested in a remote district in the Anatolian mountain range after they attacked a local police checkpoint. Five others were also injured in the attack. One of the suspects, a Swiss citizen, identified by the initials T.R., was born in Kosovo, according to reports. Appearing in court, he took pride in the attack, Turkish reports said. “It’s good to kill Turkish police,” the suspect said.

Al-Qaida in Syria has been responsible in the past for attacks against many Turkish targets, but most of these attacks took place near the Syrian border. Recently, as fierce fighting continues between the Syrian army and rebels in the border region, tensions have also risen between Assad’s forces and the Turkish military. Turkish forces even shot down a Syrian fighter jet that crossed the border on Sunday. In response, a Syrian antiaircraft unit aimed its weapons at Turkish aircraft, but did not open fire.

Turkey, one of the Syrian rebels’ biggest supporters, has been facilitating the passage of weapons and militants from its territory into Syria. The Turkish government has even recognized the organization Jabhat al-Nusra, or the Al-Nusra Front - an Islamist group also associated with Al-Qaida - as a legitimate fighting force. On the other hand, Turkish forces have clashed with militants from the Islamic State in Iraq and the Levant, as part of their ongoing conflict with various Al Qaida branches. Turkey has also dealt with Al-Qaida attacks on Turkish soil in the past, in which dozens have been killed. But until now, this Syrian branch of Al-Qaida has not been responsible for attacks in central Turkey.

American intelligence has issued warnings in recent months regarding the passage of veteran Al-Qaida militants, including mid-level commanders, from Pakistan to Syria. According to Western intelligence experts, Al-Qaida is likely to use its new base in Syria to carry out future attacks in Europe and the United States.

CIA Director John Brennan recently told Congress that intelligence indicates that Al-Qaida could use Syria to recruit new militants, as well as launch attacks that would not necessarily be restricted to Syrian soil.

Many of the extremists who worry Brennan are Pakistani Al-Qaida activists who have been the target of countless American drone strikes over the past decade. These militants bring with them to Syria combat experience, as well as extensive knowledge in explosives, light weapons, logistics, long-term planning and religious indoctrination, according to a recent New York Times report. Many experts, however, believe that these Pakistani Al-Qaida fighters do not have experience in carrying out attacks against Western targets.

Syria is attractive to Al-Qaida combatants as a base of operations far removed from American drone strikes. Al-Qaida also sees potential in the roughly 1,200 Muslims with European and American citizenship fighting there. Eventually, these volunteers for jihad could be used to carry out attacks upon returning home. Intelligence reports on the migrating of Al-Qaida combatants to Syria has been backed up by electronic intelligence, field intelligence as well as social media activity.