Ryabkov refused to say whether the missiles were on their way yet, and the Israelis promptly declared that they were not. But Israeli Defence Minister Moshe Yaalon helpfully added: "I hope they will not leave, and if, God forbid, they reach Syria, we will know what to do."
He is saying that if the missiles do reach Syria, the Israeli Air Force will attack and destroy them. But he calls it a vital issue for Israeli security, even though the missiles are purely defensive. "Security" in what sense?
In the sense that Israel sees freedom to launch air attacks on Syria any time it feels the need as a vital element of its security policy. The S-300s would make it more dangerous to bomb Syria, so Yaalon sees them as threatening Israel's "security". It's an innovative use of language, to say the least.
And then there's the European Union, which met on Monday to consider ending the blanket arms embargo against all parties to the fighting in Syria. The embargo was duly ended, and British Prime Minister David Cameron declared that it was a major step "to reinforce international efforts to reach a diplomatic solution to the conflict in Syria".
This really does require translation. What Cameron means is that with no EU arms embargo any more, individual EU members, like Britain and France, will be free to send arms to any Syrian rebel group of their choice (but not the nasty Islamists, of course). Since giving them better weapons would put more pressure on Assad to negotiate or quit, it therefore "reinforces international efforts to reach a diplomatic solution". Obviously.
And President Barack Obama most eloquently said nothing at all. He said nothing about the EU's initiative, because it's so confused and contradictory that it's embarrassing to talk about it.
He said nothing about the Israeli threat to attack the Russian anti-aircraft missiles because Israel is a "friend and ally", and it's best not to notice when its threats to attack other countries get too brazen.
And he said nothing about the Russian S-300s themselves, because he is probably secretly glad that they are being sent to Syria.
Obama is not one of the "hotheads" who want to intervene in Syria, but he is coming under increasing political pressure from those who do. Senator John McCain, the elder statesman of the Republican Party, slipped across the Turkish border into Syria for an hour on Tuesday and came back swearing that it would be easy to ensure that arms aid went only to the right rebels (not the Islamist ones).
So it helps Obama if Syrian air defences get better, because it makes the case for "no-fly zones" and other forms of military intervention even less persuasive.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries.