Russia has amassed an estimated 130,000 trips near its border with Ukraine, which has sparked a desperate round of talks as Western leaders try to avoid a war.
Vladimir Putin has had his eyes on the country for almost a decade, while claiming the West is using NATO to undermine Russia.
The UK has already supplied 2,000 anti-tank missiles, body armour, helmets and combat boots to Ukraine and Prime Miknister Boris Johnson indicated he could go further.
