The Pentagon said Wednesday that a U.S. Navy sailor was detained in Venezuela after traveling there without authorization for private purposes.

The sailor was detained last week by Venezuelan law enforcement, two defense officials said.

One official said the sailor had been in Venezuelan custody since about August 30.

“The U.S. Navy is investigating this matter and is working closely with the State Department,” the Pentagon said in a statement.

The officials, who spoke on condition of anonymity because details have not been made public, asked the State Department for an update on the sailors’ status.

One official said the soldier was not on a business trip and did not have permission to visit Venezuela.

On Wednesday, spokesman Matt Miller said the State Department was monitoring the situation but had no further comment.

The arrest follows a similar disappearance earlier this year, when a US Army soldier was arrested after he travelled to Russia to visit his girlfriend.

Staff Sergeant Gordon Black, 34, is still in Russia. In June, he was sentenced to three years and nine months in prison after his girlfriend accused him of theft.

Black is still serving in the U.S. Army, but was granted limited-duty civilian status in May, meaning he is not receiving pay, the Army said in a statement to the AP.

Last week, a lawyer for Travis King, a private who defected to North Korea last year, said King would plead guilty to desertion and four other charges and take responsibility for his actions.

During the hearing, which will be held on September 20 at Fort Bliss, Texas, King will have the opportunity to discuss his actions and explain what he did.

In December, the United States freed a close ally of Venezuelan President Nicolás Maduro in exchange for the release of 10 Americans imprisoned in the South American country and the return of a fugitive defense contractor known as “Fat Leonard,” who was at the center of a massive corruption scandal at the Pentagon.