Transparency International says 70 percent of governments fail to protect against graft in the defense sector, leaving the door wide open to waste and security threats.
The corruption watchdog says those with poor controls include two-thirds of the largest arms importers and half of the biggest arms exporters in the world.
It estimates the global cost of corruption to be at least $20 billion per year.
These conclusions are contained in Transparency International's first ever index measuring what governments do to prevent and counter defense-related corruption.
, which was released on January 29, evaluates corruption risks in the defense sector in 82 countries.
Countries with a "very high risk" of corruption in defense include Afghanistan, Iran, Iraq, and Uzbekistan.
Germany and Australia are the only countries that have strong anticorruption mechanisms according to the index.