Still, it is not clear whether the project has the United States’ official blessing. Legal experts and government officials said some of those involved with the battalion might be breaking federal laws that prohibit American citizens from training foreign troops if they did not secure a license from the State Department.

Image Sheik Mohamed bin Zayed al-Nahyan of Abu Dhabi hired Erik Prince to build a fighting force. Credit... Doug Mills/The New York Times

Mark C. Toner, a spokesman for the department, would not confirm whether Mr. Prince’s company had obtained such a license, but he said the department was investigating to see if the training effort was in violation of American laws. Mr. Toner pointed out that Blackwater (which renamed itself Xe Services ) paid $42 million in fines last year for training foreign troops in Jordan and other countries over the years.

The U.A.E.’s ambassador to Washington, Yousef al-Otaiba, declined to comment for this article. A spokesman for Mr. Prince also did not comment.

For Mr. Prince, the foreign battalion is a bold attempt at reinvention. He is hoping to build an empire in the desert, far from the trial lawyers, Congressional investigators and Justice Department officials he is convinced worked in league to portray Blackwater as reckless. He sold the company last year, but in April, a federal appeals court reopened the case against four Blackwater guards accused of killing 17 Iraqi civilians in Baghdad in 2007.

To help fulfill his ambitions, Mr. Prince’s new company, Reflex Responses, obtained another multimillion-dollar contract to protect a string of planned nuclear power plants and to provide cybersecurity. He hopes to earn billions more, the former employees said, by assembling additional battalions of Latin American troops for the Emiratis and opening a giant complex where his company can train troops for other governments.

Knowing that his ventures are magnets for controversy, Mr. Prince has masked his involvement with the mercenary battalion. His name is not included on contracts and most other corporate documents, and company insiders have at times tried to hide his identity by referring to him by the code name “Kingfish.” But three former employees, speaking on the condition of anonymity because of confidentiality agreements, and two people involved in security contracting described Mr. Prince’s central role.

The former employees said that in recruiting the Colombians and others from halfway around the world, Mr. Prince’s subordinates were following his strict rule: hire no Muslims.