US defends EU allies on arms-to-Syria

He said Russia's decision to deliver S-300 anti-aircraft missiles to the Syrian regime is a bad move because it "does not bring us closer to the political transition that Syria deserves," however.

State department spokesman Patrick Ventrell went into more detail at a briefing in Washington.

He said the EU decision will "advance" the prospect of peace by giving "the flexibility to specific EU member states to assist the opposition in a way that each sees fit."

He added: "We want [Syrian leader] Assad to have a changed calculation so that he realises that he's got to negotiate."

Ventrell also complained about Russia.

He said: "We condemn all support of arms to the regime. We've seen how the regime uses those arms. When we’re talking about the opposition, that’s a different group, and clearly they are people who are defending themselves in the face of an enormous onslaught."

The US itself has not decided if it will ship weapons to rebels.

But EU foreign ministers on Monday let each member state go its own way on arms deliveries after they failed to reach common ground in 14-hour-long talks.

The deal included a gentleman's agreement not to start arms shipments until 1 August in order not to disrupt peace talks, set to take place in Geneva in June.

But Britain and France on Tuesday said they are not bound by the August date.

British foreign minister William Hague told BBC radio: "I know there has been some discussion of some sort of August deadline. That is not the case."

French foreign ministry spokesman Philippe Lalliot told media in Paris: "Legally speaking, the [arms] embargo expires on 31 May."

He noted it would have been better if the EU had stayed united, but said national positions in Monday's talks were "very far apart," in reference to Austrian and Czech objections.

He added that France has already established logistical routes and control mechanisms for equipment deliveries to the secularist rebel group, the Free Syrian Army, by supplying it with medical aid and communications kit in recent months.

For its part, Russia said the S-300s are designed to deter Western intervention, such as the creation of a Libya-type no-fly zone.

Its deputy foreign minister, Sergei Ryabkov, accused the EU of "double standards."

He told Russian press: "The European Union ... is pouring more fuel on the fire of this conflict and damaging the prospects for convening a conference for [a] political settlement."

The Russian surface-to-air missiles cannot be used to hit rebel ground positions.

But they could shoot down Israeli planes if they get into the hands of Islamic extremists or the Assad-allied Hezbollah militia in neighbouring Lebanon.

Israel's defence minister Moshe Yaalon said on Tuesday: "The deliveries have not taken place, I can attest to this ... but if by some misfortune they arrive in Syria, we will know what to do.”

His remark comes after Israeli jets earlier this month launched strikes in Syria to stop Assad giving Russian-made arms to Hezbollah.