When you hear a politician state that he will not approve of some action others are proposing because "It will send the wrong message to (someone or some group.)" he is invariably lying. It isn't that it sends anyone any message. It's that he doesn't want the action taken but refuses to tell the true reason why he doesn't want it. Providing education on birth control to teenagers does not give them any message giving permission to have sex. They'll do that either with or without education on birth control The reason that people offer that reason is that their real reason, that getting the girl pregnant is punishment for having sex, is not something they want to be seen to say in public. Providing clean needles to intravenous drug users does not imply approval of illegal drug use. Getting aids is punishment for breaking the rules.
The current case in point - cutting off funds for the Iraq war will neither leave troops in the field with no weapons, armor or fuel, nor will leaving Iraq send any kind of message to America's enemies that we are weak and vulnerable. It might actually send a message that grownups have taken control in Washington, but no one is going to do anything different from what they intended to do because of that revelation. See Glenn Greenwald.