Trump had previously threatened military action against Venezuela, comments that feed Maduro's claim that the United States could be behind an invasion of the oil-rich country.
Trump also hasn't done anything about Citgo, Venezuela's biggest asset in the U.S.
On August 11, US President Donald Trump sent shockwaves through Venezuela's political establishment when he announced that "a military option is certainly something we could pursue" to end the South American nation's crisis.
Leaders of the fractious opposition coalition boycotted the July 30 election of the assembly.
Also on Friday, Maduro called an "urgent" meeting of American companies that buy Venezuelan oil and hold Venezuelan bonds to discuss the sanctions.More news: Trump slams GOP leaders on border wall, debt limit, health bill
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The sweeping penalties, which Trump signed by executive order, prohibit USA financial institutions from providing new money to Venezuela's government or the state oil company, PDVSA. Maduro has rallied military forces and civilians to protect the country. "We are not going to tolerate the dictatorship he's trying to create, and we're not going to respect the sham assembly".
Venezuela has been wracked by months of political crisis.
Maduro says that his new assembly was put together in order to form a new constitution which he claims "will bring peace" to the country. Trump said earlier this month that he would not rule out a "military option" in Venezuela. The event, attended by military officials from China, Belarus and Russian Federation, was a prelude to military exercises Maduro called for this weekend as a deterrent to any US military intervention.
Ever since Maduro announced there would be a Constituent National Assembly, countries from around the world - especially from the Americas - raised their voices to reject such actions as they consider them to be unconstitutional and bad for Venezuela's - already weak - democracy and division of power.
"They would bolster his discourse that Venezuela is the target of an economic war", said Smilde. With Venezuela's streets calmer than they have been for months, and the opposition reeling from its failure to prevent the constitutional assembly from going forward, action from an increasingly concerned global community represents the best chance of reining in Maduro, he added. The new decree prohibits transactions with the government of the country and its state oil company.