There was condemnation around the world after Russia launched a full-scale invasion of Ukraine.
Now Russia must be made to pay for Vladimir Putin's decision to launch an unprovoked attack, said the Norfolk-based former head of the Army.
General the Lord Dannatt was chief of the general staff from 2006 to 2009, before he retired to Norfolk.
He said he would not expect the West to become involved militarily, as Ukraine is not a member of NATO.
But he added our response should be in the form of tough sanctions, along with making it clear any further expansion beyond Ukraine would not be tolerated.
"Vladimir Putin has now launched a war on Ukraine contrary to international law, violating the sovereignty of Ukraine," he said. "We should now make Putin and Russia pay heavily.
"Frankly, he has replicated the kind of state-on-state conflict in Europe we thought we'd seen the back of in the mid 20th Century."
Lord Dannatt said the West should be "very loud" in its condemnation of Russia.
"He [Putin] has got to hear how his behaviour is is totally unacceptable," he added.
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"This miscalculation is going to hurt Russia and it's going to hurt him."
Lord Dannatt said Russia and Putin would become "the pariahs of the international community, condemning themselves to years of isolation and economic self-harm".
In a newspaper article before the invasion, he warned: "Hundreds, perhaps thousands, of Ukrainian soldiers and civilians will die as will hundreds of Russian soldiers.
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"The infrastructure of Ukraine will be smashed by air strikes and artillery fire. The West and NATO will intensify its criticism and impose the most damaging economic sanctions that can be devised.
"The world economy will stutter, and prices will rise. Perhaps Russian forces will actually enter Kiev, but what then?"
Foreign Secretary and South West Norfolk MP Liz Truss condemned Russia's "appalling, unprovoked attack" on Ukraine.
Russian President Vladimir Putin announced the action during a televised address early on Thursday morning, saying the move was a response to threats from Ukraine.
"I strongly condemn the appalling, unprovoked attack President Putin has launched on the people of Ukraine," Ms Truss tweeted.
"We stand with Ukraine and we will work with our international partners to respond to this terrible act of (aggression)."
Ms Truss on Wednesday suggested Tory donors could potentially be hit with sanctions if they have links to Mr Putin's regime.
She said she was ruling nothing out "in terms of who we target" over the Ukraine crisis, as she faced calls for her party to hand back donated cash with Russian connections reportedly worth nearly £2 million.
She added in an earlier piece for The Times that Britain will "use every lever at our disposal to stop (Putin) in his tracks", adding: "Nothing is off the table."
While NATO forces are not set to step into a direct conflict with Russia, one of the Navy's flagship aircraft carriers has been placed on standby.
HMS Prince of Wales, which is currently docked at Portsmouth, now heads the alliance’s maritime high readiness force – an international task group formed to deal with major global events.
Were NATO to step up its military support to its eastern member states such as Poland, Latvia and Estonia, the vessel would be expected to play a leading role.
The carrier's main weaponry consists of F-35 Lightning stealth fighters, which are based at RAF Marham.
World leaders have so far reacted with raw outrage - and vows of unprecedented sanctions - that shrouded a sense of powerlessness to defend Ukraine militarily without running the risk of a wider war in Europe.
Boris Johnson promised a "massive" package of economic measures in tandem with the US and European Union after the Russian president finally launched the invasion which had been feared for weeks.
In a sombre address to the nation, the Prime Minister said the world cannot stand by and allow the freedom of Ukraine to be "snuffed out", as Moscow hit its neighbour with a wide-ranging attack, targeting cities and bases with air strikes or shelling.
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