The extraordinary comments fly in the face of his previous declarations where he insisted that a European Army was a "dangerous fantasy".
On numerous occasions but notably in 2014, Clegg repeatedly denied the claims despite policy being developed at his former employer.
Indeed less than a year ago in March 2016, just months before the Brexit vote, Mr Clegg clashed with Ukip leader Nigel Farage telling him to calm down after he told the truth about the planned military strategy.
- Nick Clegg blasts 'nutty Brexiteers and Blitz survivors'
- Nick Clegg slams Prime Minister and David Davis over single market
Nick Clegg has been doing the rounds of universities in his quest for continued notoriety
It's the reason why I am still on a visa blacklist
However, during an event at University College London on Thursday Mr Clegg declared that those who supported Brexit were lying to the public.
But the irony seemed lost on him as he addressed students at the school of political sciences.
Last year during a BBC debate he said: "This is a dangerous fantasy.
"The idea that there is going to be a European airforce, a European army, it is simply not true.
"The problem with people like Nigel Farage is… they see conspiracies everywhere.
"I wouldn't be surprised if Nigel Farage soon tells us that the moon landing was a fake."
Now the 50-year-old former MEP and Lib Dem leader who described his decision to sell students down the river over tutition fees when he entered into a coalition with the Tories as a "small sin" has admitted it's true.
And he said he reverted back to project fear style rhetoric when he said he thought Britian was actually facing peril over the situation.
Get Quotes on Home Insurance
The EU has already swung into action but Mr Clegg repeatedly denied it
He told students: "The United Kingdom is out, and then crucially what the European Union and what the UK do while they are separate.
"If we were to revisit this in 40 years time and in that meantime we have turned ourselves into some bargain basement off shore Dubai economy and the European Union has created an army then clearly it will be more tricky".
In November last year Express.co.uk revealed the EU voted to ratify the creation of a continent wide army that will be up and running this year.
The new EU army is top of the agenda
At the time the EU claimed it needed to make a position of European Defence Minister to roll out its army because of Brexit.
Their report stated: "At a time when public support for the EU is being called into question in some Member States, defence and security is an area where the individual and collective benefits of more Europe can be easily demonstrated, especially regarding the likely challenges to EU’s standing as a strategic actor following Brexit."
The report demanded the EU bankroll the initiative with an immediate £76million for 'preparatory action on EU defence research' starting in 2017.
Clegg went out on the campaign trail again last year
Ukip defence spokesman Bill Etheridge said Nick Clegg had been "caught with his pants on fire."
He said: "UKIP and Nigel Farage warned about the threat of an EU Army which was dismissed by Clegg as a dangerous fantasy.
"Even he now admits we were right all along and an EU military structure is actually a dangerous reality.
"This is another example of the Remainer establishment being caught out lying just like we saw with economic forecasts, companies saying they would leave and the four horsemen of the apocalypse roaming the land."
Mr Clegg also confirmed for the first time last night that he has been blacklisted from entering Russia.
Shocking moments: When politicians fight Fri, February 10, 2017
These are the physical conflicts that occur between Members of Parliament.
EPA 1 of 12
Security officials remove members of the Economic Freedom Fighters during the State Of The Nation Address (SONA) by President Zuma in parliament, Cape Town, South Africa.
The indiscreet comments come after he refused to comment on claims that he had been stopped from visiting the country along with 88 European diplomats.
Mr Clegg talked about how his his paternal grandmother was Russian who fled the country and found a home in Britain during the war.
And he slammed US president Donald Trump claiming Prime Minister Theresa May was "weak kneed" because she flew to the US to meet him after his inauguration.
He added: "When it comes to Russia, we used to be in a pivotal position, I know this myself, it's the reason why I am still on a visa blacklist without even travelling to Russia, despite 25 per cent of the blood rushing through my veins being from Russia.
"When I was in Government I took a very, very hard line against Russia and we had clout to do so because we could mobilise opinion in the European Union to apply sanctions because of what happened in Crimea.
"We had an effective relationship with a rational US administration that would listen to our concerns and wanted to work with us, all of that is now gone, all of that is now gone.
"So I have to say I suspect what Boris Johnson or Theresa May now says about Russia will barely flicker on the Kremlin's radar screen because it is so impotent."
- EU Army set to be agreed TODAY– and BRITAIN will foot the bill
- DAWN OF EU ARMY: MEPs APPROVE new £420million-a-year EU SUPER FORCE
- British Army IN CRISIS: Major concerns as recruitment numbers plummet