Dominic Raab has said Russia will face "serious economic consequences" if they install a "puppet regime in Ukraine".
The Deputy Prime Minister and Justice Secretary said the UK will support the Ukraine to defend themselves.
But said it would be "extremely unlikely " for British troops to be sent to Ukraine to physically bolster their defence.
Last night Britain accused Vladimir Putin of plotting to install a puppet leader in Ukraine.
The Foreign Office took the unusual step of naming former Ukrainian MP Yevhen Murayev as a potential Kremlin candidate who would run Ukraine.
Mr Raab told Sky News' Trevor Philips on Sunday: "We're standing shoulder to shoulder saying there will be very serious consequences if Russia takes this move to try and invade and also install a puppet regime."
Vadym Prystaiko Ukrainian ambassador to the UK said he believes Mr Putin is capable of installing a pro-Moscow leader in the country.
"I do believe that. It's not the first time they've tried to do that," he told Sky News and added Ukraine is prepared to fight back.
Shadow Attorney General Emily Thornberry said Labour backs the Government's approach to Russian aggression.
Ms Thornberry also called for the Government to utilise a “new generation of sanctions”, including investigating the “unexplained wealth” of Putin allies living in the UK.
The unusual move from the Foreign Office came as Western allies stepped up warnings that Russia will pay a heavy price if the estimated 100,000 troops massed on the border launch any kind of incursion into Ukraine.
In a statement, Foreign Secretary Liz Truss said the Russian plotting showed the lengths to which the Kremlin was prepared go to undermine the government in Kyiv.
“The information being released today shines a light on the extent of Russian activity designed to subvert Ukraine, and is an insight into Kremlin thinking,” she said.
“Russia must de-escalate, end its campaigns of aggression and disinformation, and pursue a path of diplomacy.
“As the UK and our partners have said repeatedly, any Russian military incursion into Ukraine would be a massive strategic mistake with severe costs.”
Foreign Secreary Liz Truss has previously warned Mr Putin he must “desist and step back” from war in Ukraine or risk being dragged into a prolonged conflict like the Soviet invasion of Afghanistan.
