"That's Not a Cluster Bomb" - The Differences Between OFAB 250-270s and RBK-500s

In December 2015 Human Rights Watch and Amnesty International both published reports that included claims that Russia had used cluster munitions in its air campaign in Syria. The Russian Defence Ministry responded to those accusations by denying Russia had them at their airbase in Syria:

Concerning the suppositions on cluster bombs.

Russian aviation does not use them.

There are dozens of foreign journalists here who had been at the Hmeymim airbase and filmed the preparations for combat sorties, take-offs and landing for nearly 24 hours a day. No one even asked about this type of munitions.

That is because there are no such munitions at the Russian air base in Syria.

In response Bellingcat and the Conflict Investigation Team published images taken from RT (Russia Today), Sputnik, and even the Russian Defence Ministry’s own social media sites showing RBK series cluster munitions at the Hmeymim airbase, clearly contradicting the Russian Defence Ministry’s claims. Amnesty International also consulted a munitions expert about images from Hmeymim airbase who said “he was “confident” that many of them were indeed of Russian aircraft armed with RBK-500 cluster munitions” (page 4).

Despite these clear images and expert opinion, some have attempted to claim the bombs featured in the images were in fact OFAB 250-270 high explosive fragmentation bombs, not RBK series cluster bombs as claimed. However, it is possible to see clear differences between the RBK series cluster munitions featured in the images from Hmeymim, and the OFAB 250-270.

RBK series cluster munitions come in a selection of designs, depending on the submunition and size of the bomb. For example, the RBK-500 series cluster munitions, as seen on Russian jets in Syria, come in several varieties with differing external features. Examples include the RBK-500 ZAB-2.5M, RBK-500 AO-2.5RT, RBK-500U, and RBK-500 PTAB-1M.

However, the OFAB 250-270 has distinct features that are clearly different from the RBK series bombs. OFAB 250-270s are featured in many of the videos from Hmeymim airbase, providing many reference images for comparison to RBK series cluster munitions. The most obvious difference is the rear of the bomb:

In the above image of the rear of an OFAB 250-270 at Hmeymim airbase (source) we can see a pair of “tail rings”, and that the rear of the main part of the bomb does not extend to the end of the tail section. In the below image (source) we see a RBK series cluster munition mounted on a jet in Hmeymim airbase where we can clearly see the differences:

Only one “tail ring” is present, and the main section of the bomb extends fully to the end of the tail section. This can be seen more clearly in this photograph of a model of a RBK-500 ShOAB-0.5 cluster bomb at Ukraine’s State Aviation Museum (source):

Another clear difference is the front of the OFAB 250-270, with a distinct ridge before the front of the bomb, a slight dome on the front, and a single large fuze (source)

In a Svoboda.org article on cluster bombs at Hmeymim airbase two images from the airbase show what are believed to be RBK-500 AO 2.5 RTM cluster munitions, clearly showing the front of these munitions are very different from those of the OFAB 250-270

No RBK-500 series cluster munition share the features of the OFAB 250-270s described above, therefore claims that the munitions featured in reports about Russian cluster bombs at Hmeymim airbase show OFAB 250-270 are clearly and demonstrably untrue.