US President Donald Trump has acknowledged that he has authorised the CIA to conduct covert operations in Venezuela - a highly unusual admission of what is normally a highly sensitive and tightly guarded state secret.

The authorisation - more typically known as a presidential finding - could give the agency broad leeway to conduct operations in the region, including lethal strikes against suspected drug traffickers or broader operations aimed at destabilising or toppling the regime of Nicolas Maduro.

Previous presidential findings have ultimately led to drone strikes on militants overseas, money and weapons funnelled to insurgencies, and even efforts at full regime change.

Most, however, remain classified.

According to US law, presidents may authorise covert actions if they determine that these operations are "necessary to support identifiable foreign policy objectives...[and] important to the national security of the United States."

Once that determination is made, it must be shared with the House and Senate intelligence committees, and, in some sensitive cases, the "gang of eight" composed of leaders in both parties and the chairs and ranking members of the intelligence committees.

But that notification - which is expected to be detailed and outline legal risks - does not mean congressional approval is necessary. Congress can only block these operations through legislation or by cutting funding.

In practice, the authorisation could be as focused - or as broad - as the president deems necessary.

"The parameters of the authorities are laid out in the finding," explained Mick Mulroy, a former CIA paramilitary officer and deputy under secretary of defence.

"But there really isn't any limitations, and it does not need congressional approval."

Any restrictions imposed on the CIA's activities are executive orders, which Mr Mulroy said "means the president can simply write a new executive order and change it."

Once approved by the president, CIA actions could take the form of targeted killings, covert influence operations, shaping local politics or helping set up and equip armed rebel movements fighting foreign governments.

In December 1979, for example, a presidential finding from Jimmy Carter allowed the CIA to deliver lethal aid to Afghan guerrillas fighting the Soviet invasion of the country.

Just a few years later, another finding - this time from the President Ronald Reagan administration - allowed the CIA to extend covert aid to the Contras, rebel groups that were trying to unseat the leftist Sandinista government in Nicaragua.

More recent findings led to worldwide operations against al-Qaeda after the 9/11 attacks, as well as Operation Timber Sycamore, a CIA-run operation to train and supply Syrian rebels fighting the Assad regime.

In other countries across Latin America - including Guatemala, Chile and Brazil - the US helped overthrow governments in the name of fighting communism, or helped bolster regimes that were harsh oppressors of human rights.

"We just don't have a great track record," said Dexter Ingram, the former director for combating violent extremism at the State Department and now an advisory council member at the International Spy Museum in Washington.

"There's a long history, and it's not always positive," Mr Ingram added. "I think we have to look at our history....it's a slippery slope."

It remains unclear whether the CIA is already conducting covert actions in Venezuela, is planning to, or whether those plans are being kept as contingencies.

Trump earlier this week justified the CIA authorisation and US airstrikes against vessels in the Caribbean by saying that "a lot of drugs" are flowing from Venezuela to the US.

His disclosure about the CIA authorisation comes as US long-range B-52 bombers were seen circling near the Venezuelan coast.

CIA operations, though, would be covert and could take various different forms against an array of targets.

Suspected members of Tren de Aragua and the Cartel of the Suns, both of which the US has designated terrorist organisations, could be struck in paramilitary operations or by drones.

Marc Polymeropoulos, a 26-year veteran of the CIA who served in both Iraq and Afghanistan and oversaw clandestine missions around the world, told the BBC that the methodology of "find, fix and finish" the agency developed during the "global war on terror" could be readily applied to criminal networks.

"It's going after certain individuals, networks, or supply chains," he said. "It's manhunting, and there's nobody better on the planet at that than the CIA."

The primary difference between striking criminals in Venezuela and striking Al Qaeda or other militant targets in places like Syria, Yemen or tribal areas of Pakistan, he added, is that the latter targets mostly operated in "ungoverned" spaces.

"Conceptually, it would be a little different. Those were really lawless countries," he said. "This would obviously be done without the cooperation of the Venezuelan [government]."

Alternatively - or additionally - sabotage operations could be conducted against targets aligned to Maduro's government, "influence operations" could be used to shift public opinion through media and money, training and weapons could be provided to anti-Maduro groups - all operations with historical precedent for the CIA in Latin America and elsewhere.

"Nobody knows what this [authorisation] is," Mr Polymeropoulos added. "There's a million different questions."