The drive for Scottish independence is greeted with "bafflement" around the world, according to Foreign Secretary William Hague.
Outsiders "speak in awe" of British institutions and its stable democracy, he is expected to say in the latest UK Government intervention in the referendum debate today.
"Travelling from Afghanistan to Brazil, and from Canada to Australia, I encounter bafflement that anyone would try to break up a Union that has been so resilient, so successful and so admired as ours," the Conservative MP will tell an audience in Edinburgh.
"When outsiders look at the United Kingdom, they see one of the world's most successful examples of stable democratic government, economic development and diplomatic influence.
"They speak in awe of our institutions, our civil service and our legal systems. They admire the richness and diversity of our culture, language, history, sport and traditions, and indeed we were ranked number one in the world for soft power in one recent global survey."
Mr Hague is travelling to the Scottish capital to deliver a speech billed as setting out why the UK is stronger together, with a clear focus on foreign policy.
It is not his place to "issue dark warnings" about the consequences of a Yes vote in September next year, he is expected to say.
But extracts of his speech suggest he will set out his concerns that Scotland faces an "uncertain future" if it leaves the UK political Union.
"On the one hand is continued membership of the world's sixth largest economy, represented at the G7, G8 and G20, with a permanent seat of the UN Security Council, and an established, influential and growing diplomatic network that is increasingly focused on trade and building up links with the Commonwealth and the fastest-growing parts of the world economy," he will say.
"On the other is an uncertain future where Scots would have to face the inconvenience and tremendous burden of having to start again in world affairs, with a different passport for future generations, without that global network and enviable diplomatic position in the world, and without automatic entry to Nato and the EU."
The UK's role in the G8 summit in Northern Ireland is "tangible proof" that it is at the top table for decision making.
As well as shaping the world, British embassies promote the whole of the UK, he will argue.
"And when adventure turns to misadventure for UK nationals overseas, when there is a terrorist attack or a natural disaster, when criminals strike or British children are forced into marriage overseas, that is when we all feel the benefits of being able to turn to one of our missions in 267 posts in 154 countries and 12 territories worldwide," he will say.
"As part of the United Kingdom, Scotland derives, and will continue to derive, many benefits from being part of this global diplomatic network, instead of having to rely on inevitably fewer, smaller embassies which would take time and resources to establish."
The time and cost of creating such institutions will place an "enormous burden" on taxpayers while Scotland will "lose the benefits" of having one of "the most professional Armed Forces" in the world, he will warn.
"Not only is Scotland safer in the UK but the UK is one of the world's leading nations in human rights, development and trade because we stand strongly together: a force for good in the world, with the ability to protect the interests of our citizens at home and abroad," he will say.
Angus Robertson, the SNP Westminster leader and foreign affairs spokesman, said: "It is telling that William Hague is in Edinburgh today to lecture Scots on our place in the world, when he surely should be occupied with events unfolding in Syria.
"The test for William Hague is if he will mention the arsenal of nuclear weapons the UK government have in place on the Clyde, 30 minutes from Scotland's largest city, despite the majority of Scots being vehemently opposed. Or the UK's role in Iraq - an illegal war which cost the lives of over 100 000 civilians. Or maybe, the recent rendition flights reportedly using Scottish airports - against domestic and international law.
"Or will the Tory minister talk about the UK's role in the EU - which his party has left in jeopardy?
"One hundred and fifty countries have become independent since 1945 and countries around the world more than understand the principle of being responsible for your own decisions. As an independent country Scotland will be one of the richest countries in the world and we will play an active part in the world. As the achievements of other countries show influence is not about size, it's about working together and how you use the powers that you have."
A spokesman for Yes Scotland, the formal pro-independence movement, said: "There's no bafflement, just a clear trend - independence is the natural state for nations like Scotland. Is Mr Hague suggesting that all these countries would be better suited returning to Westminster rule?"Suggest a correction