Secretary of State Marco Rubio said Thursday that Cuba poses a national security threat to the United States and that the chance of a negotiated settlement is "not high," while President Trump told reporters at the White House that previous administrations had weighed intervention in Cuba and that it looks like he will be "the one that does it."

The twin statements, delivered a day after the Justice Department unsealed a murder indictment against former Cuban President Raul Castro over the 1996 shootdown of two civilian planes, mark the sharpest U.S. rhetorical escalation toward the island since Trump returned to office and broaden a pressure campaign that already includes a fuel blockade and an aircraft-carrier deployment to the Caribbean.

A new arrest in Miami

Immigration and Customs Enforcement on Thursday arrested Adys Lastres Morera in Miami, CBS News reported. She is the sister of Ania Guillermina Lastres Morera, the executive president of Grupo de Administracion Empresarial S.A., or GAESA, the conglomerate the Cuban military uses to control a wide swath of the island's economy. Rubio revoked her green card on Wednesday under Section 237 of the Immigration and Nationality Act.

In a social media post, Rubio said Lastres Morera "was managing real estate assets and living in Florida, while also aiding Havana's communist regime." He has previously alleged that GAESA holds $18 billion in assets and controls 70 percent of Cuba's economy. Neither Rubio nor ICE has said whether she will face criminal charges.

Havana's response

Cuban Foreign Minister Bruno Rodriguez said Rubio "lies once again to instigate a military aggression that would provoke the shedding of Cuban and American blood," according to Al Jazeera. Cuban President Miguel Diaz-Canel called the Castro indictment "a political maneuver, devoid of any legal foundation," and warned earlier in the week that a U.S. attack "would trigger a bloodbath with incalculable consequences." China said Friday it "firmly supports" Cuba and urged Washington to "stop threatening force."

A familiar pattern

CNBC reported that the administration has been conducting intelligence-gathering flights off Cuba's coast, echoing the pattern that preceded U.S. military operations in Venezuela and Iran. Separate media reports cited by the network said Cuba has been assembling more than 300 Russian and Iranian military drones for potential use against U.S. targets.

Cuba's economy is buckling. Energy Minister Vicente de la O Levy said last week the island had run out of oil and diesel, calling conditions "extremely tense." Washington has offered $100 million in humanitarian aid on the condition that it bypass GAESA.

The skeptical view

Not every analyst sees a strike coming. Antoni Kapcia, professor of Latin American history at the University of Nottingham, told CNBC the Pentagon has long judged that an invasion "would result in US soldiers in body bags on an unacceptable scale." Robert Munks of Verisk Maplecroft said Washington's posture suggests it is "letting pressure do the work."

Rubio left Thursday for a NATO summit in Sweden, where allied governments will press him on the administration's next move.