The US should respect the sovereignty of other nations and organizations with whom we have amicable relations and not monitor them. The EU, combined, is one of the world's largest economic superpowers and one of the US' largest trading partners and allies. Holding that relationship hostage by monitoring it does not send a message of goodwill on the part of the US to which the world holds us accountable for.
The EU is perfectly capable of managing itself. It isn't like the EU is a threat to us or anything... It's just an economic alliance between Europe's various nation states. Why should we get involved in that? Instead, we should work on making NAFTA as strong an alliance as the EU.