Until now, Washington has always denied it had any military intentions against Venezuela.
Domestic politics in the United States may influence the final decision on whether to sanction Venezuela's oil sector.
"It is in the best interest of the USA and the Venezuelan people to maintain our economic ties as leverage for delivering a democratic government back to the people", the letter reads. And by the way, I'm not gonna rule out a military option.
"This is our neighbor", he added.
"Trump has asked that Maduro respect Venezuela's constitution, hold free and fair elections, release political prisoners, cease all human rights violations, and stop oppressing Venezuela's great people". "But a military operation.is certainly something we could pursue".
Protests have rocked the streets of Caracas and other Venezuelan cities, both before the vote and in response to the recent political moves.
"Of course we don't support violence, but look at all the violence we're already suffering", said Irali Medina, an office administrator, pointing to the spot where a university student was killed recently by a tear gas canister fired by national guardsmen controlling protesters.
In early August, the United States has imposed sanctions on the president of venezuela that they have described as a "dictator".
Maduro said Thursday he had ordered his foreign minister to arrange a private meeting or a phone conversation with Trump.
"I am proud of the alleged sanctions. because I do not wag my tail like a lying dog", Maduro said.
"As a soldier, I stand with the Venezuelan armed forces, and with the people".
But the Pentagon said afterward that it has received no orders from the president regarding Venezuela.
If any U.S. military contingency planning is under way, it must be in its early stages.
The Pentagon said the US military was ready to support efforts to protect USA citizens and America's national interests overseas.
From New Jersey Friday, Trump would not comment on the possibility of a "regime change" in the country when it was raised during a question that also asked about the ongoing tensions between the USA and North Korea.
Trump made the remarks in response to questions from reporters at his golf club in Bedminster, New Jersey.
"Lots of good things could happen and we also could have a bad solution", he said.
Despite the heavy rhetoric, Trump declined to say if he wanted a regime change in either country.
Maduro's government responded to the latest round of sanctions by saying the U.S. was "making a fool of itself in front of the world".
Critics quickly slammed Trump for needless escalating a situation that could isolate the United States in a region that has historically opposed heavy handed measures.
"This has been going on for many years, would have been a lot easier to solve this years ago before they were in the position they are in".
We can't allow "the dictatorship to hunt down, imprison and treat our mayors like criminals", said Andres Paez, a lawyer who joined the protest.