The United States has declared Venezuela a national security threat and ordered sanctions against seven officials from the oil-rich country in the worst bilateral diplomatic dispute since socialist president Nicolas Maduro took office in 2013.
US president Barack Obama signed and issued the executive order, which senior administration officials said did not target Venezuela's energy sector or broader economy.
However the move stokes tensions between the nations just as US relations with Cuba, a key ally to Venezuela, are set to be normalised.
Mr Maduro denounced the sanctions as an attempt to topple his government.
At the end of a thundering two-hour speech, he said he would seek decree powers to counter the "imperialist" threat, and appointed one of the sanctioned officials as the new interior minister.
Declaring any country a threat to national security is the first step in starting a US sanctions program.
The same process has been followed with countries such as Iran and Syria, US officials said.
The US government said the order targeted people whose actions undermined democratic processes or institutions, had committed acts of violence or abuse of human rights, were involved in prohibiting or penalizing freedom of expression, or were government officials involved in public corruption.
"Venezuelan officials past and present who violate the human rights of Venezuelan citizens and engage in acts of public corruption will not be welcome here, and we now have the tools to block their assets and their use of US financial systems," White House spokesman Josh Earnest said in a statement.
"We are deeply concerned by the Venezuelan government's efforts to escalate intimidation of its political opponents," he added.
Mr Maduro has accused Mr Obama of a "colossal mistake" and "imperialist arrogance" similar to his predecessors Richard Nixon and George W Bush following the decision.
"President Barack Obama ... has personally decided to take on the task of defeating my government and intervening in Venezuela to control it," Mr Maduro said in a televised address.
In response, Mr Maduro said he would ask the National Assembly, controlled by the ruling Socialists, to grant him decree powers - for the second time in his nearly two-year rule through a so-called Enabling Law, which critics blast as a power grab.
Mr Maduro also paraded the seven officials, hailing them as "heroes" and naming national intelligence head Gustavo Gonzalez, whom Washington accuses of complicity in violence against protesters, as new interior minister.
