Russia has sent the largest missile shipment to date to Syria, a month after Russian President Vladimir Putin pledged to withdrawal some forces.

FOX's Lucas Tomlinson has more from the Pentagon:

U.S. officials tell FOX, Russia delivered 50 short range ballistic missiles to the Syrian port city of Tartus along the Mediterranean in the past two days.

The SS-21 short range missiles are known as "Scarabs" by NATO and depending on the type, has a range of roughly 100 miles.

In the past two days, Russia fired six ballistic missiles from its airbase in Syria against opposition fighters in Idlib, Province. It is not immediately clear if any of the opposition fighters were backed by the United States.

In December, Russian President Vladimir Putin announced Moscow's plans to scale down its military presence in Syria. But U.S. officials say Russia maintains nearly 50 war torn country.

At the Pentagon, Lucas Tomlinson, FOX News.

Follow Lucas Tomlinson on Twitter: @LucasFOXNews