Russia faces claims that it has deployed a lethal weapon capable of discharging huge firebombs across the Syrian city of Aleppo.
The machine fires 24-rocket fusillades, which produce massive chemical explosions that suck up all the oxygen in the target area, causing an intense, inescapable fireball, and massive pressure waves.
Western diplomats said on Saturday (25 September) that they were "reasonably confident" that the TOS-1A launcher, the so-called 'Blazing Sun' because of its superior firepower, has been used in the worn-torn city of Aleppo.
"We're looking into whether the Russians are using weapons we haven't seen before, like the TOS-1A, which is basically a huge flamethrower," said one western diplomat in a Sunday Times report. "It's one step down from a nuclear weapon."
The continuing offensive by Russian-backed forces was condemned by peace organisations.
"Since the announcement two days ago by the Syrian army of an offensive to capture eastern Aleppo, there have been repeated reports of airstrikes involving the use of incendiary weapons and advanced munitions such as bunker-buster bombs," said Stéphane Dujarric, a UN spokesman.
UN chief Ban Ki-moon said he was appalled by the military escalation.
The latest strikes have destroyed emergency medical clinics and bombed-out water-pumping stations have halted supplies to the city, leaving nearly two million residents without fresh water.
"What has happened in the last three days is the worst we've ever had. It's a war crime. This never happened before," said Deyaa al-Absei, an aid worker in eastern Aleppo whose home was destroyed in an airstrike on Friday (23 September) for the second time in two months. "I think they want to destroy the city and they want to destroy all the life of the people. What is happening in Aleppo is a holocaust."
The UN Security Council met on Sunday (25 September) in New York, at the request of the UK, US and France.
UK Foreign Secretary Boris Johnson said the aid convoy attack in Syria last week may have been carried out deliberately by Russian forces.
Johnson said Russian President Vladimir Putin was "not only... handing [Syrian President Bashar] Assad the revolver," he told the BBC's Andrew Marr programme. "He is in some instances actually firing the revolver himself."