"As we continue to bring economic and diplomatic pressure to bear on the Maduro regime, we hope for a peaceful transition to democracy, but as President Trump has made clear, all options are on the table," Pence said.
Pence later acknowledged to reporters that Venezuelan opposition leader Juan Guaida has sought assurances that the US could use force if necessary, but the Vice-President did not set a red line for that decision or hint at what he would recommend to Trump.
"I reassured him" that force remains an option, Pence said, "but we hope for better. We hope for a peaceful transition."
The US is running out of sanctions options, as today's announcement showed, after last month imposing sweeping penalties that effectively cut off Maduro's biggest source of hard currency - oil sales to the US. Having done that, the US has pulled the most powerful economic lever it had.
Sanctions risk worsening Venezuela's humanitarian crisis, since the nearly bankrupt government - now even more cash-strapped - is the chief importer of food and medicines. The once-wealthy nation is already reeling from hyperinflation and international penalties, and some three million Venezuelans have fled the country.
The US calculation is that the sanctions will make Maduro's rule untenable. But there are still no guarantees they will do anything more than make a bad situation worse on the ground.
The Treasury Department said it is sanctioning four Venezuelan governors aligned with Maduro, a modest step, saying they are corrupt and had facilitated the blockade of humanitarian aid to the country.
"The illegitimate Maduro regime's attempts to blockade international aid intended for the Venezuelan people are shameful," Treasury Secretary Steven Mnuchin said. "Treasury is targeting four state governors aligned with former President Maduro for standing in the way of severely needed humanitarian assistance and prolonging the suffering of the Venezuelan people."
Sanctions were placed on two governors who head states on the border with Colombia.
Omar Jose Prieto Fernandez is governor of Zulia, which the Treasury Department characterized as a hub for organised crime, drug trafficking and murder-for-hire. Prieto recently said he would declare independent if a transition government takes power in Venezuela.
Ramon Alonso Carrizalez Rengifo, is the governor of Apure. The Treasury Department said he had "endorsed" threats of violence against opposition protesters.
Also sanctioned were Jorge Luis Garcia Carneiro, the governor of Vargas who has rejected Guaido as interim president, and Rafael Alejandro Lacava Evangelista, the governor of Carabobo. The Treasury Department described Lacava as a Maduro intermediary involved in hiding overseas.
The cash flow into PDVSA - Venezuela's state oil giant - is the single largest generator of hard currency for Maduro's Government, and the US, before Trump's sanctions, was its biggest buyer. Should other countries freeze PDVSA accounts, as Pence called for, it could further pressure Maduro, but may not be decisive.
"Lima Group countries are minor players in Venezuelan oil sales," said David Smidle, of the Washington Office for Latin America, a Washington-based think-tank. "I don't think it would have a huge financial impact, but it could have a symbolic effect. From the US perspective, it would allow them to say the actions are multilateral."
