WASHINGTON - US President Donald Trump on Monday evening met with his top national security advisors at the White House Oval Office to weigh next steps, including potential land attacks on Venezuela.

According to media reports, Trump set last Friday as a deadline for Venezuelan President Nicolas Maduro to relinquish power and leave the oil-rich South American country with his family during a phone call between the two on Nov 21, but Maduro refused to comply.

During the phone call, Maduro declined the ultimatum, demanding "global amnesty" for himself and others, according to reports published Sunday and Monday.

Trump on Sunday confirmed that a call between the two leaders had occurred, telling reporters: "I wouldn't say it went well or badly, it was a phone call."

Sources told the Miami Herald, a US newspaper, that Trump sent a "blunt message" to Maduro during the phone call, amid a mounting pressure campaign in which the White House has intensified the US military buildup in the Caribbean Sea since August -- a buildup not seen in at least three decades.

"You can save yourself and those closest to you, but you must leave the country now," Trump allegedly said, offering safety to Maduro and his family "only if he agreed to resign right away."

However, Maduro allegedly refused to give up power and reportedly made his own demands, including global immunity from prosecution and being allowed to retain control of the military if he steps down.

The Miami Herald said no further contact between the two leaders has occurred, although Maduro supposedly asked for a second call after Trump closed Venezuela's airspace.

Last month, Trump said he would not rule out the use of military force in Venezuela by land to dismantle what the Trump administration calls "narco-terrorists." Critics, however, question whether counternarcotics are indeed the only US motive.

Washington has deployed around a dozen warships and 15,000 troops to the Caribbean Sea, which shares a significant amount of coastline with Venezuela. US forces have carried out at least 21 known strikes since Sept. 2 on boats suspected of carrying drugs in the Caribbean and East Pacific, killing at least 83 people.

US Secretary of Defense Pete Hegseth on Friday maintained the attacks are "lawful," following a report from The Washington Post that said Hegseth ordered the military to "kill everyone," leading to a second strike on Sept. 2 against a boat to make sure there were no survivors.

In Thanksgiving remarks to US troops on Thursday night, Trump suggested that the United States could "very soon" take actions targeting drug trafficking networks in Venezuela by land.

"We'll be starting to stop them by land," Trump said, "Also, the land is easier, but that's going to start very soon."

However, some local analysts have expressed skepticism that Trump will actually take military action.

"Maduro and most of his cohorts view the US military threats as a bluff," a source connected to top Venezuelan officials told the Wall Street Journal last month.

Brookings Institution Senior Fellow Michael O'Hanlon told Xinhua: "I doubt very much Trump would invade. But American presidents are often tempted to try regime change in the near abroad."

Christopher Galdieri, a political science professor at Saint Anselm College in the northeastern state of New Hampshire, told Xinhua the Trump administration has "made zero efforts to sell this to the country, as the (President George W.) Bush White House did for most of a year leading up to the 2003 Iraq invasion."

"The drug trafficking argument seems exceptionally flimsy," Galdieri said.

During his campaign for president, Trump "ran against US involvement in the Middle East and Ukraine, and now both of those situations continue while he may be adding a nebulous conflict with Venezuela to the mix," Galdieri said.