As the Russian invasion is into the fifth day, Ukraine said that Putin's military has used the UN prohibited vacuum bomb while attacking the country.
Oksana Markarova, Ukraine's ambassador to the US, urged the US Congress to provide more help to Ukraine which is under the brutal attack. Markarova said that the use of vacuum bombs points to Russia's aim to inflict larger scale destruction on Ukraine.
Amnesty International and Human Rights Watch have also expressed their anxiety over the use of cluster bombs and vacuum bombs on Ukrainians.
They said Russian forces appeared to have used widely banned cluster munitions, with Amnesty accusing them of attacking a preschool in north-eastern Ukraine while civilians took shelter inside.
A vacuum bomb uses 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.
Nuclear weapons are detonated by the splitting of atomic nuclei. Massive amounts of energy are released when neutrons from radioactive substances are knocked out of the nucleus, ricocheting off other atoms and causing them to split. In short, a chain reaction of splitting atoms causes a devastating explosion.
Like vacuum weapons, humans are vaporised instantly a distance from the blast. This is in part due to the rapid heat increase, causing oxygen to be sucked out of the atmosphere.
While the US promised more help by providing weapons to Ukraine, the White House seemed reluctant to consider the Ukrainian president Volodymyr Zelensky's proposal for announcing a no-fly zone for Russian flights over Ukraine. The US is said to have informed Zelensky that such a move would be tantamount to a direct conflict with Moscow.