MIAMI (AP) – U.S. Sen. Marco Rubio is warning Venezuela president Nicolas Maduro that tyrants often think they are “invulnerable” before their regimes topple.

Rubio appeared to address for the first time on Tuesday his own cryptic tweeted images over the weekend showing dictators during their brutal downfalls. The photos were shared as the Venezuelan opposition escalated efforts to force Maduro to resign.

The senator’s tweets raised eyebrows and were condemned Tuesday by Venezuela’s foreign minister who described them as a “call to murder.”

Rubio’s message has largely been cheered in South Florida where there is strong sentiment among Latin American exiles against the socialist governments of Venezuela and Cuba.