One of the most infamous moments of the bloody uprising that followed Zimbabwe's disputed 2008 election was the so-called "ship of shame" -- a Chinese freighter discovered carrying small arms, rocket-propelled grenades, and mortars to Robert Mugabe's landlocked regime. Zimbabwe's neighbors denied the ship docking rights, but the incident only reinforced the perception that China has become the arms dealer of choice for Africa's most brutal thugs, whether aged tyrants like Mugabe or the genocidal dictatorship in Sudan.

But this image may not be entirely fair: When it comes to selling guns to shady regimes, the United States is still firmly No. 1.

In a recent report for International Studies Quarterly, political scientists Paul Midford and Indra de Soysa looked at U.S. and Chinese arms transfers to Africa from 1989 to 2006, using data collected by the Stockholm International Peace Research Institute. They found no statistical correlation between China and the types of regimes it supplied with weapons, while U.S. arms shipments were slightly negatively correlated with democracy. In plain English, China actually turned out to be less likely to sell weapons to dictators than America was.

"It isn't that China is there to do good; they're pursuing their national interest," Midford says. "But we didn't find any evidence that they're trying to spread a 'Beijing consensus' or promote regimes that are specifically autocratic."

The report focuses on Africa, but similar human rights concerns have been raised about U.S. weapons transfers to Persian Gulf autocracies such as Saudi Arabia, Bahrain, and the United Arab Emirates, which collectively helped drive a more than 300 percent jump in U.S. arms sales in 2011 amid rising tensions with Iran.

Midford emphasizes that the report is not meant to suggest the United States prefers to sell weapons to dictators. "The U.S. is choosing to support autocrats based on a geopolitical rationale," Midford says, "as is China."