The Edinburgh event has been organised by The Hunter Foundation.
Ex-Defence Chiefs' Trident Warning
It would be "irresponsible folly" for the next Government not to renew Trident, a group of former defence and security chiefs have warned.
A decision against renewal would be "irrevocable", they said in a letter to The Times, adding that the submarines would have to stop patrolling the seas straight away in that case as credibility in the system would be lost.
They said the UK has made a huge contribution to nuclear disarmament but warned against compromising Britain's security in what they described as an "uncertain world".
"In an uncertain world where some powers are now displaying a worrying faith in nuclear weapons as an instrument of policy and influence, it would be irresponsible folly to abandon Britain's own independent deterrent", reads the letter signed by 20 people including former GCHQ director Sir David Omand and former head of the Royal Navy Admiral Sir Jonathon Band.
Trident is a system of submarine-based nuclear missiles, based on four boats. At any time at least one of them is at sea, on patrol, somewhere in the world.
It is operated by the Royal Navy and based at the Clyde Naval Base on the west coast of Scotland. The name Trident comes from the American-built UGM-133 Trident II missiles which are carried by the boats.
A House of Commons Library note suggests that in 2013/14 prices, replacing the whole Trident system would cost about £17.5 billion to £23.4 billion.
Yesterday Defence Secretary Michael Fallon refused to confirm the Conservatives would vote with a minority Labour government to renew Trident.
The SNP, Greens and Plaid Cymru are in favour of scrapping Trident, in contrast to the Labour and Conservative position.
Former foreign secretary William Hague said Conservative MPs would always vote for the national interest.
But he insisted it was not clear what Labour's policy on Trident would be.
He said: "The uncertainty here is over Labour's policy. We don't know what a Labour government would put to the Commons."
The former Tory leader was also asked about Mr Fallon's refusal yesterday to confirm whether the Conservatives would vote with a minority Labour government to renew Trident.
He said: "We will always be consistent with our policy but the doubt is whether Labour would put that to the Commons."
SNP leader Nicola Sturgeon outlined her opposition to Trident as she addressed a business breakfast in Glasgow
"I have opposed Trident and nuclear weapons generally for as long as I can remember," the Scottish First Minister told the event
"I just think that weapons that at the press of a button can wipe out huge swathes of civilisation are wrong. And they are in my view morally wrong."
Instead of renewing its nuclear weapons system, she said the UK should focus on conventional defence forces, saying over the last 10 years or more these had been "compromised by the obsession with the status symbol that is Trident".
Ms Sturgeon said: "Britain is an island, we're a maritime nation, yet since the Nimrods were decommissioned Britain does not possess a single maritime patrol aircraft.
"Before Christmas, in December last year, there was a suspicion that Russian submarines were patrolling in our waters. Britain had to call on America, Canada, France to come and check that out because we didn't have the aircraft to do it ourselves
"That's a sign that nuclear weapons are not just morally wrong, it's the wrong priority in terms of properly defending the country."
She argued that a large group of SNP MPs at Westminster could "force a rethink on the irrational proposal" to renew Trident at a time when "resources are so scarce".
She said: "Let me make the view of the SNP crystal clear - if there is £100 billion to spend, it should be invested in health, education and childcare, it should be invested in building a better future for our children, not on new nuclear weapons."
Temperatures in Aboyne reached 27C.
72 year old Isabella Jackson sent the abuse when Mrs May was Home Secretary.
Police Scotland Chief Constable Phil Gormley said officers had been deployed to find witnesses.
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