I saw in an article mentioning that there is a link between national debt and starting wars I don't recall where I've seen it mentioned to look for further references on the matter.  

Are there known historical studies or academic papers that examined historical data to find a causation link between national debt/trade deficits and starting wars?

Mention: When I say national debt I refer to both external debt and internal debt (both to internal debtors and through fiat currency).