Despite international calls to end its military sales to Syria, Russia has vowed to fulfill its defense contracts, citing the absence of an arms embargo. Such an embargo does not exist largely because Russia has blocked measures, including efforts at the United Nations Security Council, that might impose one.
Speaking at a conference on Tuesday before Clinton's remarks, the deputy CEO of Russia's arms export trading company Igor Sevastyanov said "No one can ever accuse Russia of violating the rules of armaments trade set by the international community."
He said Moscow will continue plans to supply Pantsyr mobile gun and missile air defense systems to Syria. Those systems could not be used to attack civilians or the opposition, but count deter a Libya-style international intervention that Russia remains opposed to.
"The contract was signed long ago and we supply armaments that are self-defense rather than attack weapons, and there can be no talk about any violations by Russia or Rosoboronexport," he said.
Multiple reports have surfaced in recent months that suggest Russia may also be supplying Syria's armed forces with small arms and ammunition, weapons that could be used in the ongoing conflict.
Russia has denied the reports. President Vladimir Putin himself addressed the matter directly during a press conference in Germany last month, telling reporters: "As for arms supplies, Russia is not supplying arms that could be used in civil conflicts."
Arms trade experts say it's almost impossible to verify such reports, since small arms and ammunition are often much harder to track and are sometimes omitted from ship manifests.
"It is possible that significant volumes of supplies of other arms have occurred without us having noticed," SIPRI's Wezeman said.
Earlier this year Cypriot authorities reportedly found ammunition on a Russian ship bound for Syria. The ship was eventually allowed to proceed to Syria, but it remains unclear what happened to the containers in question.
Last month US Ambassador to the UN Susan Rice slammed Russia over reports that another Russian ship, the Professor Katsman, was suspected of carrying arms and had docked in the port of Tartus. According to a Sunday Telegraph report this week, the ship was owned by a company controlled by Vladimir Lisin -- a Russian oligarch who has offered a $1 million reward for any Russian athlete who wins a gold medal at the London Olympics.
Meanwhile, Russia isn't the only side allegedly arming the conflict. The Independent reported this week that Saudi Arabia and Qatar are sending weapons and ammunition to the Syrian opposition.
SIPRI says confirming such reports on the ground will be very difficult, not least because foreign journalists are largely barred from entering the country.