Ignoring the NSA debate, do such actions achieve anything (from security point of view)?
Personally I don't see the need for the bellicose rhetoric emanating from Washington lately. I would think it wiser to at least appear friendly and co-operative whenever possible while warning in private up until it's time to take real measures. Then take those for real. Don't indict 5 guys you are never going to get, then make a big show of suspending conference visas. It appears paranoid and weak in my opinion. But maybe that's why I am not a policy maker.