Officials said military authorities did not authorize the travel. It remains unclear why the sailor was detained.
"My understanding was that this individual was on some sort of personal travel and not on official government business," said Kirby. "We're obviously in touch, as appropriate as you'd think we would be, with Venezuelan authorities to try and get more knowledge and information about this."
The State Department announced that it is closely following the situation, Kirby said. The sailor was detained on or about Aug. 30.
The arrest coincides with heightened political unrest in the South American nation in the wake of the July presidential election, which was marred by irregularities that sparked widespread demonstrations.
Venezuelan President Nicolas Maduro declared victory without presenting electoral data to back up his regime's self-proclaimed win. Last month, the United States formally recognized Maduro's opponent, Edmundo Gonzalez, as the winner of the election, rejecting Maduro's claim of victory. This was after Gonzalez's campaign supplied electronic copies of electoral tallies that showed Gonzalez had won the most votes.
The United States also recently moved to seize Maduro's plane in the Dominican Republic over alleged sanctions violations.
The arrest comes after a US Army man went missing earlier this year and was apprehended in Russia while visiting his girlfriend. The 34-year-old Staff Sgt. Gordan Black was sentenced to three years and nine months in prison in June after his fiancee accused him of stealing from her. He is currently serving his time in Russia, as per NBC.
