According to a US Central Command spokesman, Russian pilots have been trying to "dogfight" US jets in Syria. This is part of an aggressive pattern that has developed recently.
Col. Joe Buccino, a retired colonel, said that the Russian pilots have been aggressive in several recent incidents.
A US official said that the Russian pilots did not seem to be trying down American jets. However, they could be trying to "provoke" the US in order to 'draw us into a international incident'.
Dogfighting in military aviation is the act of engaging in aerial combat at close ranges.
Video released by US Central Command on April 2, shows a Russian SU-35 jet intercepting a US F-16 jet in an 'unsafe' and 'unprofessional' manner.
The second video, taken on April 18, shows a Russian jet that violated the coalition's airspace by coming within 2,000 feet (a distance that a fighter can cover in seconds).
In the past few years, the US has used a deconfliction zone between its military and the Syrian government to avoid any unintentional mistakes.
The official stated that US officials reached out to their Russian counterparts regarding the recent incidents. Although the Russians responded, they did not acknowledge the incident.
The official stated that since the beginning of march, Russian jets violated the deconfliction protocol 85 times. This includes flying too close to the bases of coalition forces, not reaching out to the deconfliction lines, and many other things.
This includes 26 incidents in which Russian jets armed with weapons flew over US and Coalition positions in Syria.
The official stated that 'it appears to be consistent with the new way of working'. The official said that US pilots refuse to participate in dogfights, and adhere to protocols for deconfliction.
As part of their ongoing campaign against ISIS, the US has around 900 military personnel in Syria.
Even outside Syria, Russian pilots have shown more aggressive behavior.
In March, a Russian SU-27 jet fighter collided with a US MQ-9 Reaper in international airspace above the Black Sea.
The US called the incident 'unsafe', 'unprofessional', and'reckless'.
In a recent statement, the US Air Force Central Command commander, Lt. General Alexus Grynkewich, said that the behavior was not what he expected from a professional Air Force.