Cowboy Diplomacy does not require military intervention. The threat even implied is useful for Cowboy Diplomacy but you don't need to actually go to war.

Cowboy Diplomacy is just the term used to describe a foreign policy that uses bullying techniques, being harsh, not being diplomatic.

Think of Roosevelt's famous line, "speak softly, but carry a big stick". Think of Reagan and how is image was one of attacking first and diplomacy as an afterthought.

It is risky policy and hard to pull off successfully. Reagan did it in part because people were a bit afraid he wasn't bluffing. It is doubtful Obama could pull it off even if he was prone to trying it.

The word 'cowboy' is usually used to invoke the image of the lone figure, who does what he wants (or feels he has to do) no matter what the consequences are. If you want to follow him, you're welcomed to, but he's not going to ask your permission; he's not afraid to ride off alone.

The Wikipedia article in this case is short and fairly poor. It doesn't fit with my understanding of the term, but I have no sources readily at hand with which to counter it.