How to treat a country name that has a plural meaning

There are many cases where an entity that's made up of plural words is singular. Obviously, the United States of America is a single entity, so "has" is right. This isn't an exception; this is the rule.

Unlimited Designs, a Delaware corporation, has gone out of business.

CSS (Cascading Style Sheets) is a great way to style your webpages.

Strictly speaking, you should handle it on a case-by-case basis. In everyday usage (i.e., probably anything short of official diplomatic correspondence), stick with the singular.

(Background: Before the American Civil War of 1861-65, it was customary to say "The United States are...". Before the war, the US was a much looser federation of sovereign states than it is today, culturally as well as politically: a resident of Virginia would have considered herself a citizen of Virginia first and of the United States second. The war greatly strengthened the national bonds between the states, even to the point of changing the language: after the war and ever since, people have said "The United States is...". So there's precedent for treating a single nation-state as plural, but in the modern world it's not something that's likely to come up.)

The comprehensive article on plurals at Wikipedia ( http://en.wikipedia.org/wiki/English_plural ) includes the following:

Geographical plurals used as singular

Geographical names may be treated as singular even if they are plural in form, if they are regarded as representing a single entity such as a country: The United States is a country in North America (similarly with the Netherlands, the Philippines, Trinidad and Tobago, etc.) However if the sense is a group of geographical objects, such as islands or mountains, a plural-form name will be treated as plural: The Hebrides are a group of islands off the coast of Scotland. [end quote]

This leads to different treatments when the same descriptor is used for both region and features:

The North West Highlands is a key area in the history of geological science.

...the North West Highlands are the mountains I love ...

(both Google; however, usage often illogically crosses over)