In an interview with CNN on Sunday, US Senator Marco Rubio warned that President Nicolas Maduro would face grave repercussions if the Venezuelan government harmed or imprisoned opposition leader Juan Guaido, who declared himself the country's interim president last month.
"There are certain lines and Maduro knows what they are. The consequences will be severe and they will be swift," Rubio said, also warning Maduro not to harm US personnel working in the country, adding that the United States would also respond if aid workers were targeted.
Rubio declined to say if he would support possible US military action against Venezuela, but added that the Trump administration would not stand by if Maduro cracks down on Guaido.
He spoke a few days after Guaido called on the Venezuelan Armed Forces, supporting President Nicolas Maduro, to change sides, in the anticipation of humanitarian aid arrivals to the crisis-hit country.
Tensions have further escalated ahead of 23 February, when US "humanitarian aid", which is currently stockpiled in Columbia, is expected to reach Venezuela.
The deadline was set by Guaido despite strong opposition from Maduro, who slammed it as a ploy to topple the Venezuelan government, instead demanding that Washington lift the economic sanctions imposed on Caracas.
"It's a booby trap, they're putting on a show with rotten and contaminated food […] They've stolen $30 billion and are offering four crumbs of rotten food," Maduro claimed.
Guaido was almost immediately recognised by the United States and its allies after he proclaimed himself Venezuela's interim president on 23 January, with Trump then telling CBS that the US military intervention in Venezuela remains "an option".
Russia and China, among a spate of other nations, say that they recognise Maduro as Venezuela's only legitimate president.