Venezuela's President Nicolás Maduro has accused the US of plotting to kill him and topple his government.
He told reporters that US National Security Adviser John Bolton was personally involved in the plot, but did not produce any evidence.
President Trump has labelled the leftist leader a dictator and has imposed sanctions.
Earlier this week the US criticised the arrival of two Russian bombers in Venezuela.
The Russian Tupolev Tu-160 bombers are capable of carrying nuclear weapons.
What did Maduro say?
"John Bolton has been assigned with the job organising my assassination, deploying foreign troops and imposing a transitional government in Venezuela," he told journalists at the Miraflores presidential palace.
The Venezuelan people were prepared to fight back, with the help of "friendly countries," he added,
Mr Maduro has previously accused the US as well as Colombia and the Venezuelan opposition of plotting to kill him.
What was behind the visit by Russian bombers?
The US is increasingly concerned by his government's links with Russia, China and other countries that have differences with the Trump administration.
US Secretary of State Mike Pompeo said the Russian bombers' visit amounted to "two corrupt governments squandering public funds".
The Russian government called his words "completely inappropriate".
The long-range strategic bombers landed at Simón Bolívar airport outside of the Venezuelan capital, Caracas, on Monday along with two other Russian planes.
Venezuelan Defence Minister Vladimir Padrino said they were part of air force exercises with its Russian allies: "This we are going to do with our friends, because we have friends in the world who defend respectful, balanced relations."
How deep is Venezuela's economic crisis?
More than two million people have fled Venezuela since 2014, about 7% of the country's population.
Venezuela says the US has waged an economic war to put an end to almost 20 years of socialism in the country.
Mr Maduro blames the US policies and sanctions for the high inflation and shortage of food, medicines and other goods.
On Monday, the American tyre maker, Goodyear, announced it was halting operations in the country.
"Our goal had been to maintain its operations, but economic conditions and US sanctions have made this impossible," said Goodyear in a statement.
Its employees in Venezuela have each been given 10 tyres as part of their severance payment.
A number of foreign firms, including Kellogg and Clorox, have pulled out of Venezuela, citing a growing economic crisis and US sanctions.