Russia's military yesterday announced that it had successfully tested a lethal new air-delivered bomb, which it described as the world's most powerful non-nuclear weapon.
In what appears to be the Kremlin's latest display of military might, officials said Moscow had developed a new thermobaric bomb to add to its already potent nuclear arsenal.
Russia's state-run Channel One television said the new ordnance - dubbed the Father of all Bombs - is four times more powerful than the US's Mother of all Bombs.
"The results of tests of the aviation explosive device that has been created have shown that it is comparable with nuclear weapons in its efficiency and potential," Alexander Rukshin, a deputy chief of the Russian armed forces staff, told the channel.
"You will now see it in action - the bomb which has no match in the world is being tested at a military site," the report said. It showed a Tupolev 160 strategic bomber dropping the bomb over a testing ground. A large explosion followed.
The aviation vacuum bomb, which is also known as a fuel-air bomb, was the mightiest ever created, it added.
Last night's announcement comes at a time of growing tension between Russia and the west, and follows a tumultuous eight months in which Vladimir Putin has denounced US power, torn up a conventional arms agreement with Nato, and grabbed a large, if symbolic, chunk of the Arctic.
Last month Russia carried out a series of war games with China and four other central Asian states, designed to show the country's resurgent military power and the emergence of new regional alliances outside Nato. Russia's strategic nuclear bombers also resumed patrols of the Arctic, Pacific and Atlantic oceans.
The development of this latest device appears to be another response to the Bush administration's plans to site elements of its missile defence system in central Europe. Mr Putin has denounced the plan, arguing that it upsets Europe's strategic balance, and has vowed to respond.
The US Massive Ordnance Air Blast, nicknamed the Mother of all Bombs, is a large-yield satellite-guided, air-delivered device, which previously enjoyed the dubious accolade of the most powerful non-nuclear weapon in history.
Thermobaric weapons differ from conventional explosive weapons by using oxygen from the atmosphere, rather than carrying an oxidising agent in their explosives. They produce more energy than normal weapons but are hard to control.
The US used similar fuel-air munitions to clear jungle for helicopter landings during the Vietnam War. The Soviet Union also developed its own fuel-air weapons, deploying them against China and in Afghanistan, and the Russian army used them in its second war in Chechnya.
The new bomb comes at a time when both Russia and the US appear to be reneging on nuclear arms limitation treaties signed during the cold war and after the collapse of the Soviet Union.
Yesterday the head of a Russian foreign policy thinktank warned that Russia and the US were on the brink of a new cold war involving "an unrestricted nuclear and conventional arms race".
Relations could sink into a serious crisis in a few years, and "domestic and political factors will aggravate the situation rather than help overcome the differences", Sergei Rogov, director of the Russian Academy of Science's US and Canada Institute, told the academy's presidium.