The choice facing the people of Scotland in September is clear.
It's a choice between further devolution to the Scottish Parliament, with the strength, security and stability of being part of the larger UK or taking a leap into the unknown with separation.
As an MP for an English constituency, I am very clear that this is a matter for the Scottish people to decide. I don't have a vote, but I do have a voice. My message to people in Scotland is simple: the UK would be much diminished without Scotland and Scotland would be much diminished outside the UK.
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Think of the huge contribution Scots have made to the defence of the whole of the UK, from warships built by men on the Clyde that saw service in the D-Day landings to the thousands of men and women across Scotland who are today serving on the front line on behalf of people across the UK.
Thousands of Scots employed in our defence industry make the equipment and develop the technology necessary to make sure we have the best armed forces in the world.
Since the mid-1980s half of the UK's defence secretaries have been Scottish. Scots have been at the very heart of UK defence decision making for all of my political lifetime.
I will be in Scotland today to make the case that staying in the UK is best for Scotland's defence, and best for Scottish jobs. In the morning I will visit a specialist company in the East End of Glasgow that benefits from UK MoD contracts.
Like so many employers in Scotland, being part of the UK is good for jobs and good for business. The jobs of thousands of Scots in our defence industry are secured by being part of the UK.
One thing we know beyond doubt is that leaving the UK would cost defence jobs in Scotland. The government of the continuing UK would have to seriously consider whether it could continue to place key defence contracts with Scottish firms if there were a Yes vote in September. The idea that, somehow, everything would carry on as it is just because Alex Salmond says so simply isn't credible.
In the afternoonI will speak at a Forces Together event for undecided voters in Greenock and around Inverclyde. Like so many communities in Scotland and elsewhere in the UK, there is a proud defence tradition in Greenock and the surrounding area.
Men and women from Greenock gave their lives fighting against the Nazis during the Second World War. The Free French Memorial that stands above the town commemorates its role in harbouring the Free French Forces who were stationed there during the war and hundreds of people still make a living working in the yards on the Clyde and at Rosyth.
For those in Inverclyde who have done their bit to secure the freedoms we often take for granted, it didn't matter that colleagues were from different parts of the UK.
What is great about the UK is that we can all have our own unique identity, culture and history but that doesn't stop us sharing something great. You can be proud to be Scottish, English or Welsh and a proud Brit at the same time. We don't have to choose between the two. Only Alex Salmond wants to force that choice on the people of Scotland.
I want to be the UK Secretary of State for Defence, and hope to be so after the General Election in 2015. I want that UK to include Scotland. The people of the United Kingdom are safer and more secure if we work together as one rather than break apart and try in vain to recreate what we once had.
Working together across the four nations of our isles is a profoundly modern and positive vision. When contrasted with the fundamental negativity of the divisive plan to break up the UK, there can be no doubting which side is running the more positive campaign.
Our UK armed forces and defence industry are the best in the world. We should keep it that way by keeping the UK together.