While often ignored, Britain still maintains a "one service, one medal" ideology, where multiple medals for the same service are not permitted (ignoring, of course, the World Wars). This is the policy behind the witholding of permission to wear for the Kuwaiti and Saudi medals for Gulf War II. As the UK has its own medal for Afghanistan, the NATO medal is seen as a duplication. As far as the US is concerned, clasps seem to be seen as frivilous European frippery (ignore, please, the WWI Victory Medal, the "Wake Island" clasp, etc.). As the various UN medals are collapsed to a single generic ribbon for the US, NATO clasps are disallowed. Who ever said "policy" had to make logical sense?