Britain is supplying Ukraine with short-range anti-tank missiles for self-defence after Russia amassed about 100,000 troops on its border, the defence secretary said.
Ben Wallace told MPs a small team of British troops would also be sent to Ukraine to provide training.
He said there was “legitimate and real cause for concern” the Russian troops could be used for an invasion.
Russia denies any invasion plans and accuses the West of aggression
Dozens of British troops have been in Ukraine since 2015 to help train their armed forces, and the UK has also made a commitment to help rebuild Ukraine’s navy following Russia’s invasion of Crimea in 2014.
Mr Wallace also said the UK would be providing extra help with security in the light of Russia’s “increasingly threatening behaviour”.
The first batch of light anti-armour weapons was sent on Monday, although the defence secretary did not specify the type.
“Ukraine has every right to defend its borders and this new package of aid further enhances its ability to do so,” he told MPs.
“Let me be clear: this support is for short-range and clearly defensive weapon capabilities; they are not strategic weapons and pose no threat to Russia; they are to use in self-defence.”