Donald Trump has ordered a “total and complete” blockade of oil tankers under sanction going into or leaving the South American country of Venezuela, in what media reports in the USA have called a “major escalation” .

The United States and Venezuela have been facing off for weeks, as Trump increases a campaign of mounting pressure against the country’s leader, Nicolás Maduro.

Taking to his own social media platform, Truth Social, the US President posted: “Venezuela is completely surrounded by the largest Armada ever assembled in the History of South America”.

There are currently U.S. warships, aircraft and thousands of troops in the region.

President Trump warned that his county would increase a military presence in the area and that “the shock to them will be like nothing they have ever seen before” as he demanded Maduro’s regime give back oil, land and other assets which the President claimed had been stolen from America.

It was reported as a reference to the South American countries nationalisation of U.S-linked holdings in the country. Earlier this year Trump threatened to order land strikes inside the country itself.

It is not currently known how many tankers will be affected, and how much the U.S. army will be involved in implementing the blockade.

This latest escalation comes just days after the Americans seized a tanker full of crude oil from the country, and the White House said that there would be even more seizures. Many tankers are stuck off the coast of Venezuela, with shipping data showing vessels making turns at sea rather than risk being intercepted by the U.S.

Fears of escalation and a border impact have only grown, as Venezuela’s government has, in recent years, made use of Iranian and Russian-linked tankers to avoid U.S. sanctions that disallow the trading of the country’s crude oil.

Russia has had a long-standing closeness with the South American country, however that has recently become stale, with experts telling the BBC that Moscow has not provided any material support to the country.

However, the Kremlin has said Putin called President Maduro to affirm his support.

“The president of the United States is trying in an absolutely irrational manner to impose a supposed military naval blockade on Venezuela to steal the riches of our homeland,” Venezuela’s government said in a statement. “Venezuela will never go back to being a colony of the empire, nor any other foreign power.”

Whilst a military blockade is considered an act of war, the President appears to have fallen short of instructing a full one. The current blockade excludes the US company Chevron, which operates in the country and is exporting oil under a license which stops sanctions applying.

Earlier this week a spokesperson for the company told the Wall Street Journal that its operations in the South American country were continuing without disruption,and in full compliance with the law.

“It is international law 101 that a military blockade is not just a violation of the UN Charter, but a crime of aggression,” unless such a move is in response to an armed attack, Ryan Goodman, a professor of law at an American University said on social media.

Since a tanker was seized last week, there has been a drop in vessels waiting to call into ports in Venezuela.

Last month, the U.S. Navy’s largest aircraft carrier, the USS Gerald . Ford arrived in the region, along with a strike group that included other warships. Stealth fighters and more are currently being staged in nearby Puerto Rico, and aircraft able to refuel bombers mid-flight have been moved to the Dominican Republic.

Trump’s claims that the country had “stolen” American assets have been met with confusion from critics

“No country in the Western Hemisphere has ever suffered a blockade that shuts off its primary source of export revenue,” Francisco Rodriguez, a Venezuelan economist at the University of Denver told the WSJ.

“Trump is demanding that a new Venezuelan administration carry out a massive transfer of its oil wealth to the United States. This quite obviously violates both Venezuelan and international law,” Rodriguez added.

More recently the country has accused America of being behind a cyber attack which crippled a state-run oil exporters’ systems, and suspended tankers from leaving the country. There are currently more than 10-million barrels of oil aboard tankers around the country.