Mr Lord West has said the world should “get a grip and make some sensible moves” when dealing with Russia and Vladimir Putin.
The former First Sea Lord described the Russian leader as a “crook” and said Mr Putin thinks he can “get away with anything”.
Admiral Lord West said: “For someone to have carried out any attack on our soil is extraordinary.
“And it’s certainly tied to Russia because of the nerve agent used.
“It could have killed British people on the street, and in the old days of imperial rivalries nations went to war over things like this.
“This is very very worrying indeed – one has to show [Putin] how serious this as he seems to think its some kind of game.”
Lord West, who had a 50-year career in the armed forces, added that conflict would be “catastrophic” and that “no one wants to go to war”.
Britain and Russia’s diplomacy is at a low following the poisoning of Sergei Skripal.
The Kremlin has continued to deny any involvement and dismissed all accusations that the Kremlin was behind the attack.
Admiral Lord West said even if Mr Putin was not behind the attack, he would have known about it alongside Kremlin officials.
He told the Daily Star online: “I think at the moment, because of this behaviour, there is a very real risk with the way [Putin] keeps going that by accident something might happen that no one wants.
“It doesn’t take much for something like that to escalate – and that would be catastrophic for everyone really.
“That really worries me, everyone needs to get a grip and we need to make some sensible moves.”
He went on to say: “Putin hates the fact there are powerful liberal democracies around the world, and he would like to see all of those at odds and in a mess,” he said.
He added: “That would make him very happy.
“I am afraid that all the indicators are that President Putin doesn’t believe that any of the norms of behaviour between international powers apply to him.”
His spokesman Dmitry Peskov said that Russia is “perplexed and does not comprehend the British leadership’s stance” and insisted the “accusations are unsubstantiated”.