The base is primarily known as a controversial detention center for suspects accused of terrorism-related offenses, but it also has a history of being used to hold migrants, dozens of whom were sent there in recent weeks.

Hegseth wrote on X that he was "wheels up" for the trip, during which he will tour base facilities "and receive briefings on operations supporting illegal immigrant deportations."

A Pentagon announcement on 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 United States began flying migrants to Guantanamo earlier this month, some of whom have already been repatriated, but US Southern Command said Tuesday that there are currently "17 high threat illegal aliens" who arrived over the weekend and are being held there.

The Trump administration has launched what it cast as a major effort to combat illegal migration that has included immigration raids, arrests and deportations on military aircraft.

The Guantanamo prison was opened in the wake of the September 11, 2001 attacks and has been used to indefinitely hold detainees seized during the wars and other operations that followed.

Conditions there have prompted outcry from rights groups, and UN experts have condemned it as a site of "unparalleled notoriety."