Britain's international partners are aghast, mostly in silence, at the possibility one of the leading Western powers could break up and turn in on itself if Scotland votes for independence from London.
Many fear such a split would foreshadow a British exit from the European Union, on which Prime Minister David Cameron has promised a referendum in 2017, weakening the world's sixth largest economy and its continental partners.
Some also fear it would set a precedent, boosting separatism in Catalonia and elsewhere in Europe. Independence campaigners from around the continent have underlined this by flocking to Edinburgh to support the “Yes” campaign in the September 18 vote and to draw lessons for their own struggle.
Some posed for a group photograph with Scottish nationalist leader Alex Salmond, now racing to turn narrowing opinion polls into a win in the September 18 vote.
The idea is not sitting well in leading capitals.
U.S. President Barack Obama has been forthright in urging Britons to stay together and in the EU.
“We obviously have a deep interest in making sure that one of the closest allies that we will ever have remains a strong, robust, united and effective partner,” Obama said on a visit to Europe in June.
U.S. Navy Secretary Ray Mabus, while stressing it was up to the Scottish people to decide, underlined this week the importance of Scotland in building Britain's aircraft carriers and as the base for its nuclear submarine force.
“It would be unwise for an American to take sides in this, but there would be some issues that would require some serious work,” he told a Reuters Summit on Wednesday.
Privately, U.S. and European officials say they are concerned that a Britain amputated of a third of its territory and 8 percent of its population would be more introverted and less
While France has said it is willing to join Obama in air strikes against Islamic State militants in Iraq, Cameron has played for time and avoided a clear commitment so far.
Last year Cameron failed to win parliamentary support for joining proposed U.S. air strikes in Syria, reinforcing opposition in the U.S. Congress that eventually prompted Obama to abandon the plan.
European partners have tried to be quietly supportive of Cameron on Scotland, underlining how keen they are to keep Britain in the EU, while privately puzzling over his decision to risk everything on two uncertain referendums.
“A Scottish exit from the union [with England, Wales and Northern Ireland] would be bound to heat up the debate about an early referendum [on leaving the EU],” said Phillip Missfelder, foreign policy spokesman for Chancellor Angela Merkel's conservatives in the German parliament.
Merkel has made clear Berlin wants to keep Britain in the EU and is willing to accommodate some of London's demands for changes to help Cameron win the in/out plebiscite he has promised if he is re-elected next year.
Publicly, she has avoided taking sides, saying: “There's a fair campaign taking place. So I have nothing to criticize. I also think the British are not waiting for advice from the German chancellor on what to do, let alone the Scots.”
But German Foreign Minister Frank-Walter Steinmeier was less diplomatic on Thursday. “I would openly admit that I would rather see Great Britain remain together,” he told a news conference in Berlin with his British counterpart Philip Hammond.
In highly centralized France, it is the precedent of separatism that is causing most political anguish.
“The idea that this can happen in Europe in regions like Scotland - even though it isn't at all the same context - demonstrates that frontiers are exploding and this is worrying,” said Socialist lawmaker Patricia Adam, who chairs the parliament's defense committee.
Some European diplomats are alarmed by Cameron's high-wire strategy for trying to hold the country together and in Europe. “How could he take such ill-calculated risks?” a French diplomat asked privately.
He pointed to France's own history of lost referendums that brought down President Charles de Gaulle in 1969, stopped a proposed EU constitution in 2005 and very nearly killed off Europe's single currency before it was born in 1992, when voters approved the Maastricht Treaty by a whisker.
If Scotland does vote for independence, its future status with the EU could be a matte
European Commission chief Jose Manuel Barroso infuriated nationalists in February by saying a breakaway Scotland would have to reapply for EU membership and would find it “extremely difficult, if not impossible” to gain unanimous approval.