What is a vacuum bomb?
UKRAINE claims a vacuum bomb has been used in a strike by the Russians.
The high-powered weapon uses the atmosphere to create a deadly explosion - and it is deadly to anyone in proximity of its blast.
What is a vacuum bomb?
A vacuum bomb is also known as a thermobaric weapon.
It uses the oxygen of the surrounding air to produce a high-temperature explosion.
The blast wave produced is significantly longer than typical condensed explosives.
They are among the most powerful non-nuclear weapons ever developed.
Thermobaric weapons are almost 100 percent fuel so create a far more energetic blast than many conventional explosives.
How deadly are vacuum bombs?
A vacuum bomb can vaporise humans in close proximity and can crush internal organs.
As the oxygen is sucked out of the atmosphere, the rapid heat increase can even kill those at a distance away.
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Thermobaric weapons can be destructive against buildings and are effective at destroying defensive positions.
The deadly bunker-busting bomb was used by US forces for the first time in Afghanistan, , in 2002.
The bomb by deployed by US warplanes south of the Afghan city of Gardez where intelligence had discovered a concentration of Taliban and al-Qaeda fighters.
Are vacuum bombs illegal to use in warfare?
Vacuum bombs and cluster bombs are banned under the Geneva convention.
Ukraine's ambassador to the United States Oksana Markarova said Russia used a vacuum bomb in the early stages of the war.
After briefing members of the US congress on February 28, 2020, she said: "They used the vacuum bomb today, which is actually prohibited by the Geneva convention.
"The devastation that Russia is trying to inflict on Ukraine is large."
White House Press Secretary Jen Psaki said if Russia was using cluster and vacuum bombs against Ukrainian civilians it would "potentially be a war crime".
Dr Marcus Hellyer, senior analyst at the Australian Strategic Policy Institute, told it was yet to be confirmed if one had been deployed, but it was only “a matter of time”.
Ukraine president Volodymyr Zelenskyy said residential areas in Kharkiv had been bombed by Vladimir Putin's regime.
He said: "No one in the world will forgive you for killing peaceful Ukrainian people."
President Zelenskyy said there will "definitely be an international tribunal".
Which countries have vacuum bombs?
Thermobaric weapons were developed by the Soviet Union and the United States in the 1960s.
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Russia created an explosion equivalent to 39.9 tons in September 2007 when it detonated the biggest thermobaric weapon ever.
Fears are rising Russia will use thermobaric weapons on Ukraine after Putin launched his deadly invasion.