Moscow - Russia is preparing to counter the strategic threat posed if the US sites a missile defence base in eastern Europe with military measures including specially modifying its ballistic missiles, a Russian military expert said Thursday.

"Russia's military responses to the deployment of a US missile defence system in Europe may include improving the Russian strategic Topol-M missiles with hypersonic manoeuvering warheads and a large number of jamming stations that would reduce the effectiveness of missile defence elements tenfold," said Viktor Yesin, a former chief of General Staff of the Russian Strategic Missile Troops.

The United States has failed to convince Russia that plans to site parts of a missile shield in Poland and the Czech Republic are intended only to guard against rogue states such as Iran. Russia views the shield as a threat to its Cold War nuclear deterrent.

Yesin said the Russian military was considering a full range of measures to adequately to responded to the perceived threat from the US system.

Such plans include reactivating Soviet military plans to place ballistic missiles in orbit form where they would be able to bypass the planned US shield through the via the South Pole.

"Russia can already now carry out such technical measures and is partially doing so," Yesin was quoted by news agency Interfax as saying.

He listed among other possible military counter measures the deployment of a missile system in Russia's European enclave of Kaliningrad and readying long-range Tu-22 M3 bombers for missions.

Yesin also suggested that Russia was considering pulling out of the Russian-American Strategic Offensive Reduction Treaty, which commits both countries to reduce nuclear warheads by nearly two- thirds by 2012.

In December, Russia withdrew from key Cold War-era arms restraint treaty in what analysts say was partly military anger at US missile defence plans. But Yesin advised restraint Thursday, saying it was not a time to scare European allies. (dpa)