The vote over Scottish independence is coming down to the wire. Polls show a close race. It is a momentous decision that would reverse the Act of Union adopted back in 1707, but why is President Barack Obama bothering the Scots with his opinion?

A Scottish yes vote would have dramatic effects. While independence activists have reassured their countrymen that nothing much would change, a Scottish nation might find a less than warm welcome from European and other world leaders. No doubt, Holyrood (parliament) would receive diplomatic recognition. But Scotland's passage to nationhood might not be as easy as promised.

An independent Scotland likely would have to reapply to the European Union and NATO. Holyrood would have to create its own currency, or unofficially use the British pound, over which the Scots would have no control. The new nation would have to decide whether it even wanted a military; the British nuclear deterrent would have to move south to a base that today doesn't exist.