Scud: 'Entry level' ballistic missile
"A stunning, desperate and a disproportionate escalation."
That's the verdict of the White House spokesman Jay Carney to reports that Syrian government forces have fired more than a dozen Scud-type missiles from the Damascus area into northern Syria.
The Syrian Foreign Ministry though has strongly denied using such weapons.
However, Nato sources speak of allied intelligence, surveillance and reconnaissance assets having detected the launch of a number of unguided, short-range ballistic missiles inside Syria this week.
"The trajectory and distance travelled indicate that they were Scud-type missiles," Nato says.
This seems to be the first time that the Scud - originally a lumbering Soviet-designed ballistic missile of Cold War vintage - has been used in the Syrian conflict.'Entry level' missile
This, though, is by no means the first time that Scud missiles have been used in anger.
Indeed the Scud - alongside the German V2 rocket of World War II - is one of the most-used ballistic missiles in history.
Egypt fired Scud missiles against the Israeli bridgehead established on the western side of the Suez Canal in 1973.
Libya fired Scud missiles at a US facility on the Italian island of Lampedusa in 1986 after US air strikes against Libya.
They were used by Soviet forces in Afghanistan and by the Iranians and Iraqis during their bitter conflict.
More recently, they were used by Saddam Hussein's Iraq against Israel and Saudi Arabia in the Gulf War.
And there are reports of their use by Libyan government forces during the civil war there in 2011.
The Scud is in many ways an "entry level" ballistic missile.Inaccurate weapon
Indeed, the basic technology is little different from the V2 rocket developed by Nazi Germany.
The name really refers to a family of weapons with ranges of up to 300km (187 miles).
It is a short-range ballistic missile that uses liquid fuel. It is launched vertically from a small platform - usually mounted on a wheeled transporter-erector-launcher.
A ballistic missile has a high-arcing trajectory. It leaves the earth's atmosphere during the powered phase of its flight - it then goes into free-flight before the re-entry stage when it plummets back to earth.
Gyroscopes guide the rocket during the powered stage of its flight - the missile being equipped with movable fins.
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However, once the motors shut off it effectively coasts to its target meaning that it has notoriously poor accuracy. Scuds can carry nuclear, chemical and conventional high-explosive warheads.
The Soviet Union exported Scud technology widely among its allies in the developing world.
From there the technology was often re-exported, so - for example - it is suggested by experts that North Korea's missile programme began when it received Scud missiles from Egypt.
Some countries set up their own production facilities.
The precise type of missile used by the Syrians in recent weeks is unclear. Some experts believe it could be a improved version of the basic Scud - exported by North Korea.
The use of such an inaccurate weapon against rebel targets is curious. It seems to have little military logic, though may be intended to shock President Bashar al-Assad regime's opponents.'Barrel bombs'
Some military pundits have suggested that it is an indication of the losses being suffered by the Syrian air force and the fact that a number of air bases have been overrun by rebel fighters.
There is no doubt that the government is losing aircraft to rebel gunfire and surface-to-air missiles.
The disruption inside the country may be causing logistical problems, and it has never been clear just how much of the Syrian air force President Assad can count upon.
However, aircraft can potentially hit targets with some accuracy. Scuds cannot.
Their use seems to reflect a growing pattern over recent weeks of the regime having recourse to more and more indiscriminate weapons - improvised "barrel bombs", for example, dropped from helicopters.
Human Rights Watch has also documented the use by the Syrian regime of cluster bombs containing incendiary submunitions.