What is Vacuum bomb that Ukraine claims Russia is using

Ukraine's ambassador to the United States, Oksana Markarova, accused that Moscow had used a thermobaric weapon, known as a vacuum bomb.

Ukraine's ambassador to the United States and human rights groups have accused Russia of using cluster bombs and vacuum bombs on Ukrainians as the war rages in and around Kyiv. The weapons have been condemned by a variety of international organisations including Amnesty International and Human Rights Watch.

The organisations said that Russian forces appeared to have used widely banned cluster munitions, with Amnesty accusing them of attacking a preschool in northeastern Ukraine while civilians took shelter inside. Meanwhile, Ukraine's ambassador to the United States, Oksana Markarova, accused that Moscow had used a thermobaric weapon, known as a vacuum bomb.

"They used the vacuum bomb today. The devastation that Russia is trying to inflict on Ukraine is large," the ambassador told reporters. The Ukrainian claims are yet to be confirmed on the ground and Reuters quoted White House Press Secretary Jen Psaki saying, "If that were true, it would potentially be a war crime." She noted that there are international organisations that would assess that and President Joe Biden's administration "would look to be a part of that conversation."

With the advancement of technology and the fast-paced nature of warfare, weapons have been upgraded too. While most weapons rely on explosives to throw metal fragments to destroy targets, a new class of ammunition is focussing on blast as their primary output. Thermobaric weapons are one such tool that uses the effects of temperature and pressure on the target.

A vacuum bomb, or thermobaric weapon, sucks in oxygen from the surrounding air to generate a high-temperature explosion, typically producing a blast wave of a significantly longer duration than that of a conventional explosive and is capable of vaporizing human bodies.

Also known as an aerosol bomb, it is a two-stage munition with the first charge distributing aerosols made up of very fine material from a carbon-based fuel to tiny metal particles. The second charge ignites that cloud creating a shock wave sucking up the oxygen and making a vacuum around its target. Experts have warned that the blast wave of a vacuum bomb lasts significantly longer than traditional explosives.

Amnesty International said international humanitarian law prohibits the use of inherently indiscriminate weapons such as cluster munitions. Launching indiscriminate attacks that kill or injure civilians constitutes a war crime. Dr. Marcus Hellyer, senior analyst at the Australian Strategic Policy Institute, told The Guardian that while vacuum bombs will not be used to penetrate a tank, they could be a very destructive weapon against an apartment complex or other building.