US President Donald Trump has been ramping up pressure on Venezuela's leader, President Nicolás Maduro.

The Trump administration has doubled the reward for information leading to Maduro's capture, and its warships are within striking distance of Venezuela. Dozens of people have been killed in attacks on boats alleged to have been transporting drugs from the South American country.

Trump reportedly also gave Maduro an ultimatum to leave Venezuela, in a phone call the two men had on 21 November.

Nicolás Maduro rose to prominence under the leadership of left-wing President Hugo Chávez and his United Socialist Party of Venezuela (PSUV).

Maduro, a former bus driver and union leader, succeeded Chávez and has been president since 2013.

During the 26 years that Chávez and Maduro have been in power, their party has gained control of key institutions, including the National Assembly, much of the judiciary, and the electoral council.

In 2024, the electoral council declared Maduro the winner of the presidential election, even though voting tallies collected by the opposition suggested that their candidate, Edmundo González, had won by a landslide.

The US is one of many countries which declared the election illegitimate and recognised González as "president-elect".

But with Maduro firmly in control of the military, the police and the legislature, he has remained in power and González has fled into exile for fear of arrest.

Trump has made stopping immigration a priority during his second term in office and he blames Maduro for the arrival of a large number of Venezuelan migrants in the US.

Since 2013, close to eight million Venezuelans are estimated to have fled the economic crisis and political repression in Venezuela, which have both worsened under Maduro.

Most have fled to Latin American countries, but hundreds of thousands have gone to the US.

Without providing evidence, Trump has accused Maduro of "emptying his prisons and insane asylums" and "forcing" its inmates to migrate to the US.

Trump has also focused on fighting the influx of drugs - especially fentanyl and cocaine - into the US.

As part of his war on drugs, he has designated two Venezuelan criminal groups - Tren de Aragua and Cartel de los Soles - as Foreign Terrorist Organisations and has alleged that the latter is led by Maduro himself.

Maduro has vehemently denied being a cartel leader and has accused the US of using its "war on drugs" as an excuse to try and depose him and get its hands on Venezuela's vast reserves of oil.

Analysts have pointed out that the Cartel de los Soles is not a hierarchical group but an umbrella term. They say it is used to describe corrupt Venezuelan officials who have allowed cocaine to transit through the country.

The US has deployed 15,000 troops and a range of aircraft carriers, guided-missile destroyers, and amphibious assault ships to the Caribbean.

The stated aim of the deployment - the largest in the region since the US invaded Panama in 1989 - is to stop the flow of fentanyl and cocaine to the US.

Since early September, US forces have carried out more than 20 strikes in international waters on boats alleged to have been carrying drugs. More than 80 people have been killed in the strikes.

The Trump administration argues that it is involved in a non-international armed conflict with the alleged drug traffickers, whom it accuses of conducting irregular warfare against the US.

The US has also described those on board as "narco terrorists" but legal experts say the strikes are unlawful as that designation "did not transform them into lawful military targets".

A former chief prosecutor at the International Criminal Court told the BBC that the US military campaign fell into the category of a planned, systematic attack against civilians during peacetime.

In response, the White House said that President Donald Trump acted in line with the laws of armed conflict to protect the US from cartels "trying to bring poison to our shores... destroying American lives".

Counternarcotic experts have pointed out that Venezuela is a relatively minor player in global drug trafficking, and that it acts as a transit country through which drugs produced elsewhere are smuggled on their way to their final destination.

Its neighbour, Colombia, is the world's largest producer of cocaine but most of it is smuggled to the US by other routes, not via Venezuela.

According to a US Drug Enforcement report from 2020, almost three quarters of the cocaine reaching the US is estimated to be trafficked via the Pacific with just a small percentage coming via fast boats in the Caribbean.

Nevertheless, most of the strikes the US has carried out have been in the Caribbean, with just a few in the Pacific.

In September, Trump told US military leaders that the boats targeted "are stacked up with bags of white powder that's mostly fentanyl and other drugs, too".

However, fentanyl is produced mainly in Mexico and reaches the US almost exclusively via land through its southern border.

Trump has confirmed that he spoke to Maduro on the phone on 21 November.

While he did not reveal what was said in the call, Reuters news agency reported that Trump gave Maduro a one-week ultimatum to leave Venezuela along with his close family. It said that Maduro did not take him up on the offer of safe passage.

One day after the deadline expired, Trump declared the airspace around Venezuela closed.

Trump has already threatened to take action against Venezuelan drug traffickers "by land", but has not specified how such an operation would unfold.

Trump's press secretary has also not ruled out the possibility of US troops being deployed on the ground in Venezuela, telling reporters that "there's options at the president's disposal that are on the table".

She did not elaborate further on the options but military analysts have for weeks pointed out that the US deployment in the Caribbean is much larger than needed for a counternarcotics operation.