The UK's shared defence forces provide the "security and peace of mind" which underpin almost every area of the debate on Scottish independence, defence secretary Philip Hammond has said.
A Yes vote in September would also result in "long and protracted negotiations" over defence issues such as the Trident nuclear weapons at Faslane, according to Hammond.
His latest intervention follows the publication of the UK Government's Defence Analysis Paper, and comments from firms working in the sector.
Speaking at electronics company Thales Optronics in Glasgow, the defence secretary is expected to outline his arguments for Scotland remaining in the UK, touching on issues such as Trident and the Scottish Government's proposals for a currency union.
He will say that defence "provides the security and the peace of mind that underpins almost every single other area of this debate".
He will add: "What we have is precious ... It is our shared history, our common values and our unity of purpose which makes us what we are today. It is Scotland which makes the UK united, and adds the Great to Great Britain.
"Drawn from the four corners of these islands, nothing epitomises more the strength we derive from being a United Kingdom than the men and women in our Navy, Army and Air Force, coming together with a common purpose, to keep our country and our people safe and secure."
Hammond will say that a formal currency union between Scotland and the rest of the UK is "not an item up for negotiation".
On Trident, he will say: "He (Scotland's First Minister Alex Salmond) also wants to dictate the timescales for removing our nuclear deterrent within the first term of Parliament following independence.
"But Alex Salmond knows, as I know, that the future of our naval base at Faslane would be just one of many defence issues that would be the subject of long and protracted negotiations if there were to be a Yes vote in the referendum.
"Because if they insist that it has to go, there would have to be complex talks about the costs and timescales involved. Any notion that it would be quick and easy is just plain wrong."
Also today the First Sea Lord has claimed the "very heart" of Britain's maritime defence forces would be damaged by Scottish independence.
Admiral Sir George Zambellas insisted the nations that remained in the UK would adapt and cope eventually but he said Scotland would feel a "deeper impact" if it broke away.
Writing in the Daily Telegraph, Sir George said: "I believe that independence would fundamentally change maritime security for all of us in the United Kingdom and damage the very heart of the capabilities that are made up of the Royal Navy, the Royal Marines, the Royal Fleet Auxiliary and the Fleet Air Arm.
"While the continuing United Kingdom would eventually adapt and cope, the deeper impact would be felt in Scotland, which would no longer have access of right to the security contribution of one of the finest and most efficient navies in the world."