Sir Michael Fallon held global security talks with Nato’s Secretary General Jens Stoltenberg and ambassadors at the home of the UK’s nuclear deterrent to mark the 350th nuclear submarine patrol.
He said the UK would continue to play a leading role in Nato’s deterrence missions, emphasising the £1.3 billion investment planned for the base over the next ten years.
The visit came a day after Scotland’s First Minister Nicola Sturgeon reaffirmed her commitment to removing nuclear missiles from Scotland.
Speaking at Holyrood, she said: “I want to see a world free of nuclear weapons and I think that countries such as the United Kingdom should lead by example.
“Instead of spending tens of billions of pounds on a new generation of Trident nuclear missiles, we should get rid of Trident nuclear missiles from the Clyde.
“We will continue to support action for unilateral nuclear disarmament because, if countries lead by example, the world will be a safer place in the long term as a result.”
Responding to the comments, Sir Michael said the SNP needed to “sort out” their position on the nuclear deterrent.
He said: “As I understand it the SNP position seems very confused now. They want to join Nato, Nato is a nuclear alliance and our nuclear forces, the French nuclear forces, the American nuclear forces are part of Nato’s nuclear alliance.
“The nuclear deterrent here today keep Britain safe, it keeps Nato safe as well and Scotland is part of that.”
The base on the Clyde has been home to the submarine based nuclear deterrent for five decades, with investment planned to update and upgrade its engineering and training facilities.
It will be home to the entire UK submarine service by 2020, with the number of jobs it supports expected to rise from 6,800 to 8,500 in the 2030s.
The delegation’s visit included a tour of a UK Vanguard class deterrent submarine and the base’s Trident training facility.
Ambassadors also toured a Royal Navy frigate taking part in Exercise Joint Warrior, the UK-led multinational exercise due to begin on Sunday which has its operational headquarters on the Clyde.
One of the largest military exercises of its kind in Europe, it brings together 35 naval units from Belgium, Canada, Denmark, Estonia, France, Germany, Italy, Latvia, Lithuania, the Netherlands, Spain and the US, as well as aircraft from Canada, France, Norway, the UK and US.
SNP MSP Bill Kidd said: “As Defence Secretary Michael Fallon has overseen catastrophic cuts to the defence footprint in Scotland, which have left the UK unable to even patrol its own waters - and he has betrayed shipyard workers on the Clyde by breaking promises repeatedly made on them.
“Much of the cuts to the defence budget are as a result of the Tory government continuing to plough money into its Cold War era weapons of mass destruction, which are totally ineffective against the key threats of the 21st century.
“The SNP’s opposes Trident renewal, a majority in the Scottish Parliament oppose Trident renewal, most of Scotland’s MPs oppose Trident renewal and the majority of people in Scotland oppose Trident renewal.
“We want Scotland - like most countries in the world and the majority of Nato members - to be free from nuclear weapons.”