Tensions are rising between Turkey and Russia as officials reported on Monday that Syria had intercepted a Russian fighter plane after it violated Turkish airspace near the Syrian border.

The incident occurred Saturday in the Yaladagi region of Turkey’s southern Hatay province. The Russian plane was intercepted by two F-16s of the Turkish air force. Immediately after the situation, Turkey summoned Russia’s ambassador to protest the violation and warn Russia not to repeat the same mistake in order to keep the situation from escalating.

The Anadolu news agency quoted Turkish Prime Minister Ahmet Davutoglu: “Whoever violates our airspace, our rules of engagement are clear,” he said. “We will warn whoever violates our borders and our airspace in a friendly manner. This country can be whichever and Russia is our neighbor, our friend. In this way, there is no tension between Turkey and Russia. The Syria issue is not a Turkish-Russian crisis,” he said.

However, Turkey and Russia are at odds in Syria concerning their position on Syrian President Bashar al-Assad. Turkey believes al-Assad should step down from his position for the conflict to end while Russia supports al-Assad.

NATO Secretary General, Jens Stoltenberg, met Davutoglu on Monday. He stated that the Russian violation of Turkish airspace was unacceptable and an emergency meeting regarding the issue would take place later in the day.

“Russia’s actions are not contributing to the security and stability of the region,” Stoltenberg said. “I call on Russia to fully respect Nato airspace and to avoid escalating tensions.”

U.S. officials believe the Turkish airspace violation was deliberate and the kind of unpredictable act they have feared since Russia began building up its military presence in Syria last month.

“I don’t believe this was an accident,” said a senior U.S. defense official, speaking on condition of anonymity to discuss deliberations with Turkey and other NATO allies. “This is exactly the type of unprofessional, non-professional incident we were hoping to avoid.”

According to Dmitry Peskov, a spokesman for Russian President Vladimir Putin, Russia is currently looking into reports of the violation, but at this time, Russia has made no further comment regarding the issue.