I wish the press would call her out on using the term "leverage". If the US military confront Russia's proxies at the no-fly-zone and force them to turn back, then this would given them leverage against Russia. That's what the term implies. Changing that situation on the ground and then going to Russia and saying "now what". When Clinton uses the term "leverage" it's misleading voters, who don't realize that enforcing the no-fly-zone will require confronting Russian planes directly.