Given the difficult security environment in Iraq, overhead was expected to run closer to 10 percent.

Rather, we are in a new national security environment.

However, while the security environment has improved, you should exercise caution, particularly at night.

Be particularly cautious after dark in the current security environment.

The national security environment that exists today is significantly more complex than a year ago.

Such a development is, of course, highly unlikely in the present benign security environment.

That is a profound change in the national security environment.

The proposed budget says, "the security environment has become more difficult in recent years."

"Iraq is going to be a pretty difficult security environment for a while."

There's going to be a different security environment in this city.