Only the U.S. government is restricted from hiring mercenaries under what is known as the Anti-Pinkerton Act of 1893.

Are mercenaries still used today?

Recent years have seen major mercenary activity in Yemen, Nigeria, Ukraine, Syria, and Iraq. Many of these for-profit warriors outclass local militaries, and a few can even stand up to America's most elite forces, as the battle in Syria shows. The Middle East is awash in mercenaries.

Are US military contractors mercenaries?

Mercenaries are often called military contractors. The difference between them “comes down to labels,” says Sean McFate, a former Army officer who's also worked as a private military contractor. He wrote about the use of contractors in his book, “The New Rules of War.”