According to Russia’s Izvestia newspaper, the Russian military has deployed a substantial new group of warplanes into Syria, to be operated out of the Hmeymim base, near Latakia. The Russian Defense Ministry has yet to confirm the new deployment, which is said to include more advanced planes.

The move reflects increased fighting, particularly in the area around Aleppo, and a desire by Russian officials to get more forces into the region as the US threatens unspecified “non-diplomatic” actions against them for continuing to fight against the Nusra Front in Aleppo.

Russia has a substantial number of airplanes operating inside Syria, but the most advanced planes they have simply can’t operate out of the runways available to them inside Syria. This has forced them to fly from southern Russia, and briefly from an airbase in Iran, though Iran quickly put a stop to that in the face of some diplomatic tensions.

Since the ceasefire in Syria collapsed a week and a half ago, the Russian military has been increasing its aid to the Assad government, particularly as it relates to fighting ISIS and Nusra. They have also spurned US demands to halt all attacks and ground all their planes, insisting that the US is a big reason why the ceasefire ended unsuccessfully.