US Defence Secretary Pete Hegseth has described Guantanamo Bay as a "critical temporary stop" in the processing of illegal immigrants.
His comments came after he toured the detention facilities set up by the new US administration to house undocumented migrants.
The base is best known for holding suspected militants swept up in the wake of the September 11, 2001, attacks, but President Donald Trump last month announced that it would hold up to 30,000 undocumented migrants as part of his sweeping clampdown on illegal immigration.
“Arrived at Naval Station Guantanamo Bay on the front lines of the war against America's southern border,” Mr Hegseth wrote in a post on X that included a video of him saluting and shaking hands with troops at the base in south-eastern Cuba, where he once served as a military officer.
He later posted that he had toured the detention facilities at the base, describing it as “a critical temporary stop in processing these dangerous illegal aliens for eventual removal from our country”.
A Pentagon announcement on Mr Hegseth's trip said it “underscores the department's commitment to ensuring the security and operational effectiveness” of the base and “provides an opportunity to engage with the dedicated service members and personnel who play a vital role in the base's mission”.
The US began flying migrants to Guantanamo earlier this month, with more than 170 of them repatriated to Venezuela last week.
US Southern Command said on Tuesday that there were “17 high-threat illegal aliens” who arrived at the base over the weekend and are being held there.
The Trump administration has launched its major effort to combat illegal migration, conducting immigration raids, making arrests and deporting people, some via Guantanamo.
The American Civil Liberties Union (ACLU) and other advocacy groups said this month that they had filed a suit seeking access to migrants held at the base.
