In times of great threat on the ground during the Syrian crisis, even the skies see their fair share of close calls. On Wednesday, a Russian fighter jet approached a U.S. warplane in Syrian airspace for identification purposes, as it sought to put to rest the fears of mid-air collision that the U.S. has been worried about.

While the Russian warplanes were bombing Islamic State group targets in Syria's Aleppo province, one of their Su-30 SM fighter jets "detected emissions from an unidentified flying object," defense ministry spokesman Igor Konashenkov said. "Our fighter turned and flew to a distance of two or three kilometers (one to two miles from the plane), not with the intention of scaring someone, but to identify the object in question and to whom it belonged," he said in his statement, according to AFP.com.

Russia began its campaign of air strikes in Syria on Sept. 30, saying it was targeting Islamic State militants and other jihadist groups after a request to help militarily from Syrian President Bashar al-Assad. However, Syrian activists and Western countries claim that the Russian planes have been hitting non-militant targets - which Moscow denies.

In another incident, two shells struck the Russian embassy compound in the Syrian capital Damascus as hundreds of pro-government supporters rallied outside in support for the Russian air strikes on Tuesday. Although no one was killed, a BBC Arabic correspondent in Damascus reported that some people were injured, according BBC News.

The attack, however, is not the only form of retaliation that Russia has faced. On Monday, Russian security officials had to arrest several people who had ties to the Islamic State group plotting to target the Moscow transportation system .

An Islamic State spokesperson posted an online message on Tuesday "calling on Muslims everywhere" to launch a jihad against Russia and the U.S. "Russia will be defeated," IS spokesman Abu Mohamed al-Adnani said in a recording posted online.

"If the Russian army kills the people of Syria, then kill their people. And if they kill our soldiers, then kill their soldiers. An eye for an eye," al-Jolani said, according to AOL News.