“We have pushed back the perimeter and we'll have eyes in the sky, so we'll be keeping a close look on it. But I just want to caution people, that with things of this nature, you can never have 100 percent guaranteed security, but what you do is try to be prepared in the event that something does go astray,” Johnson told reporters following a news conference at a South Loop police station. “So I think that we put things in place now to keep everybody safe. We want everybody to have an enjoyable time.”