Mark Pritchard, MP for The Wrekin, said the Ukraine now represented the frontier between democracy and Vladimir Putin's autocratic Russia.
Following Boris Johnson's announcement that the Government would be imposing sanctions on Russian banks in the wake of its invasion of Ukraine, Mr Pritchard said it was important to offer more support to countries such as Poland and Estonia which were now feeling vulnerable to attack.
Mr Pritchard, who is chairman of the all-party parliamentary group or the Ukraine, said: "Ukraine is not Nato's border yet, it is not the EU's border yet, but it is democracy's border today.
"This house stands in full solidarity with our counterparts in the Rada (the Ukrainian parliament) and the people of Ukraine, including the people of Donetsk and Luhansk."
Mr Pritchard said the Prime Minister had referred to Britain's partners in Nato.
"Can I ask him what more reassurance and practical support we can give to Nato members like Poland and the Baltic states who today are just a little bit more fearful?"
The Prime Minister said Mr Pritchard was right to draw attention to the Baltic states and to Poland.
"In Poland, as he knows we've increased our support with another 315 marines from 45 Commando, in Estonia we have doubled our presence in Tapa to 2,000, we're doing more in the high north in Romania and elsewhere and we will continue to keep all these projects under constant review.
"We and other European countries are stiffening the eastern frontier of Nato."
Meanwhile Stone MP Sir Bill Cash said it was vital that measures being taken in the face of Russian aggression were successful.
"Escalating economic sanctions against Russia and fully effective defensive support for Ukraine can never be allowed to fail," he said.
Sir Bill said Russia and President Putin's aggression affected all its European neighbours, and had an ever-increasing global reach, including even in places like Africa.
Mr Johnson agreed that an aggressive and expansionist Russia was a threat not just to Europe but to the whole world.
"It is up to the UK to push back, and that is what we're going to do," he said.
Michael Fabricant, MP for Stone, referred to Neville Chamberlain's failure to contain Hitler after he took control of the Sudetenland in 1938.
"Eighty-five years ago, a predecessor of the Prime Minister talked about 'a quarrel in a far away country of between people of whom we know nothing'," he told the Commons.
"Doesn't the concordance between both sides of the house today, demonstrate this is not the case when it comes to Ukraine?"
Mr Johnson said there was a large Ukrainian community in Britain which made a valuable contribution to this country.
He said anybody who knew anybody from this community would feel huge sympathy for the people of the Ukraine.