The UK underestimates the threat to its future security posed by Russia, shadow defence secretary Liam Fox has warned.
Liam Fox says Russia is stepping up defence spending
Addressing a fringe meeting at the Conservative Party conference, Dr Fox claimed Russia was increasing its defence spending this year by 25%.
It was also testing more long range missiles and pouring money into two naval bases in Syria, he added.
That, together with Iran's military build-up, justified replacing Britain's Trident nuclear weapons system.
Dr Fox said the Tories were committed to replacing Trident nuclear weapons and, with so much uncertainty in the world, he warned against embarking on a "potentially lethal experiment in unilateral disarmament".
He said Iran and Russia pose the most serious "potential threats to our interests".
He said Russian President Vladimir Putin had spoken recently "of having armed forces capable of fighting a global, regional and, if necessary, a few local conflicts".
The shadow minister said he had been "amazed" by how little coverage Russia's new military build-up has received in the Western media.
He said the country was spending 25% more on defence this year than last year and is testing new inter-continental ballistic missiles, and ordering new frigates for its navy, equipped with cruise missiles.
The Russians have also reportedly invested in two Syrian ports, he added.
If they switch their Black Sea fleet there it would be their first Mediterranean base since the 1950s, said Dr Fox, who repeated his warning in a speech in the main conference hall at the Bournemouth conference centre.
He also said that, along with North Korea and China, Russia had helped Iran to develop ballistic missiles with a range up to 4,000 kilometres which "could attack US and British forces in the region".
And he warned of the economic power being wielded by Russian gas giant Gazprom, which he said was controlled by "extremely questionable oligarchs and politicians".
If President Putin went on to be the head of Gazprom after stepping down as Russian president, he would be able to wield a "great deal of influence" over neighbouring states, Dr Fox told the meeting.
"It might turn out President Putin is a cuddly bunny. It might turn out that he is not. We should be in the risk business," he added.