US Secretary of State Marco Rubio said Thursday that the likelihood of a negotiated agreement with Cuba is not high at the moment.

"In the meantime, we'll keep doing what we need to do," Rubio told reporters before leaving for a NATO foreign ministers meeting in Sweden.

The United States has recently indicted Cuban Revolution leader Raul Castro in connection with the Cuban military's fatal downing of two planes 30 years ago and sent the Nimitz Carrier Strike Group to the Caribbean, moves seen as part of a broader pressure campaign against Cuba.

However, US President Donald Trump said Wednesday there will be no escalation in Cuba.

Cuban President Miguel Diaz-Canel on the same day condemned the US government's indictment of Cuban revolutionary leader Castro, stressing that the Cuban people would not tolerate insults against their history and national heroes.

He also described the US indictment of Castro as a "political maneuver" with no legal basis, adding that Washington "is lying and manipulating the events surrounding the downing of the small planes belonging to the narco-terrorist organization Brothers to the Rescue."

Previously, Cuba had repeatedly stressed that it is a peaceful country that poses no threat to the national security of any other nation. Havana said US threats of military aggression had reached a "dangerous and unprecedented level," but emphasized that Cuba would not yield and would firmly defend its national sovereignty and independence.

(With input from Xinhua)