Grant Shapps urged European countries outside Nato to consider joining the defensive alliance in the face of an aggressive Russia.
The Defence Secretary warned it is important for like-minded nations to “stand together” against the threat from Vladimir Putin.
As the alliance marked its 75th anniversary yesterday (THURS), ministers met in Brussels to discuss the invasion of Ukraine.
Mr Shapps said: “Russia’s aggression in Europe has already led to Nato expansion.
“I’ve no doubt others will want to consider whether it’s time to join in with our collective security.
“It’s important for Europe’s defence that we stand together.”
Nato has grown from 12 founding members to 32 member countries, including recent additions Finland and Sweden.
Austria, Ireland, Cyprus, Malta are among nations that remain outside the alliance.
Nato countries are committed to help defend members if they come under attack.
Despite allies agreeing a decade ago to spend at least 2% of national income on defence spending, most failed to do so.
But this year, 18 are expected to hit the target.
Prime Minister Rishi Sunak said Nato is the most successful defensive group in the world bringing together 3.5 million uniformed personnel in collective defence.
He said: “The UK has been at the heart of Nato since the start. Today, faced with new threats in Europe, we continue to lead – through our incredible armed forces, our growing investment in defence, and our utter determination to stand by Ukraine – which has strengthened allied unity like never before.
“I say it once again: Ukraine’s rightful place is in Nato.
“This anniversary is the moment to renew our historic pledge to this Alliance and to say that no matter who tests us, we will not waiver.”
