Sekouba Konate, a former Guinean president and serving African Union general, has pleaded guilty to smuggling money into the US.
The 51-year-old tried to sneak in more than $64,000 (£42,600) after arriving on a flight from Ethiopia in 2013.
He faces up to five years in jail when he is sentenced next February, said the US Department of Justice.
Known as "El Tigre" for his military prowess, he was in the junta which took power in December 2008.
Gen Konate handed over power in December 2010, after Guinea's first democratic elections in 50 years.
Afterwards he was appointed general commander of the security forces of the African Union, US court papers said.
Hide and seek with $64,770
- Gen Konate filled in a US declaration form stating he was carrying not more than $10,000
- After this was queried twice by US customs officers, he admitted he was carrying $14,000
- A preliminary search revealed $30,750 in US currency concealed in various compartments of the general's luggage
- He signed another form admitting he was carrying $44,750
- A second, more thorough search found an additional $20,020 - again concealed in luggage compartments
- He repeatedly said the questioning was improper given his status as a former president and current commanding general of the African Union forces.
Source: US Justice Department statement
According to the Associated Press agency, Gen Konate, who had been due to go on trial on Tuesday, has family in North Carolina and owns property in the state.
He testified at a pre-trial hearing that he did not understand the customs process because of language barriers, the agency reports.
Prosecutors said he claimed to have $10,000 or less when he arrived at Washington Dulles International Airport in June 2013 and did not declare the other cash he was carrying, much of which was hidden in his luggage.
His lawyer asked the court to exclude at trial any statement regarding the source of the money, the Wall Street Journal newspaper reports.
"Mr Konate is not charged with, for example, money laundering, which would put at issue the source of funds," a document filed by the defence on 25 November said.
As part of his plea agreement, the parties agreed that $61,770 was properly seized and that $3,000 would be given back to the general as "humanitarian aid", Reuters news agency reports.
Gen Konate served as an interim president in Guinea for about a year having taken over leadership of the junta after coup leader Captain Moussa Dadis Camara was shot and injured in 2009.
At the pre-trial hearing, a customs agent testified that there had been suspicions about Gen Konate because of his property purchases in North Carolina, AP reports.