U.S. Imposes New Sanctions on Venezuelan Regime

“There can be no bystanders in Venezuela’s struggle for freedom,” Mr. Pence said in a speech. The U.S.’s top ally in the region, Colombia has taken in a third of the more than 3.4 million migrants the United Nations says have fled Venezuela’s economic meltdown, marked by food and medicine shortages, since 2015.

The vice president’s comments come as the region debates how to resolve Venezuela’s political and economic crisis. Mr. Maduro’s security forces repelled humanitarian-aid caravans that tried entering from Colombia and Brazil over the weekend.

At least four people were killed and more than 300 injured in skirmishes among anti-Maduro protesters, Venezuelan soldiers and armed paramilitary groups called colectivos that are loyal to Mr. Maduro.

In the aftermath, Mr. Guaidó’s aides called for international force to oust Mr. Maduro. Key members of the Lima Group, however, including Brazil, Chile, Peru and Panama have vociferously rejected any military action in a region where citizens are overwhelmingly opposed to U.S. intervention.

“The permanence in power of Nicolás Maduro and his illegal regime represents an unprecedented threat to the security, peace, freedom and prosperity of the whole region,” 11 Lima Group nations said. But the group didn’t specify steps it would take to support Mr. Guaidó and reiterated its stance that any transition toward democracy must be “without the use of force.”

Mr. Pence said he reassured Mr. Guaidó that all options remained on the table, but that the hope was for a peaceful transition.

Some analysts said the opposition’s calls for force was a blunder that could hurt its international coalition and undermine bipartisan support in the U.S. Over the weekend, Sen. Chris Murphy (D., Conn.) questioned whether the aid delivery was just a pretext to start a war with Venezuela.

“It weakens the coalition, it also weakens the bipartisan consensus in the United States over Venezuela,” said Michael Shifter, head of the Inter-American Dialogue, a Washington policy group. “That is a loss of a major asset.”

Others warned that any intervention in Venezuela would be difficult given the ideological nature of the regime, irregular forces such as paramilitaries and guerrilla groups, and weak state institutions.

“The idea that military intervention could be surgical and not have horrendous unforeseen consequences is massively irresponsible,” said Cynthia Arnson, a scholar on conflict resolution at the Woodrow Wilson Center in Washington. “I don’t see a Syria comparison far-fetched.”

From the U.S. supporting a military coup in Chile to arming paramilitary groups during civil wars in Central America, Washington’s long history of intervention in the region has left Latin Americans largely wary. Critics, also pointing to the upheaval that has ensued following the U.S.’s regime-change efforts in the Middle East, say those interventions have destabilized nations, contributing to widespread bloodshed and human-rights abuses.

Mr. Pence said the U.S. would continue to push for humanitarian aid, with a new contribution of $56 million to support programs for Venezuelan migrants.

The U.S. and its allies are also identifying new places along the border to stockpile aid, he said. Last weekend’s showdown was confined to an official crossing with Brazil and at three bridges that connect to Colombia. But there are thousands of miles of unpatrolled areas along Venezuela’s sparsely populated western and southern borders.

On Monday, the U.S. Treasury added four Venezuelan state governors close to Mr. Maduro to a list of nearly 70 officials that have been blacklisted and had their U.S. assets frozen. Two of them are governors of Venezuelan states bordering Colombia, while another, Rafael Lacava, had served as an intermediary for Mr. Maduro, the Treasury said.

“These men work to block aid for people in need,” Mr. Pence said, promising stronger financial sanctions on Venezuela in the coming days. “We will work to find every last dollar that they’ve stolen and return it to the Venezuelan people.”

Spokesmen for the governors didn’t immediately respond to calls seeking comment. Mr. Lacava had helped negotiate the release last year of Joshua Holt, a former Mormon missionary from Utah who along with his Venezuelan wife spent nearly two years in a Caracas prison on espionage charges.

The Maduro regime, which didn’t immediately respond to the latest measures, routinely dismisses U.S. sanctions as efforts to topple the government. Despite Colombia’s migration authority reporting the defection of at least 270 soldiers, National Guard troops and police officers in the past few days, Mr. Maduro’s aides claimed victory and say they are undeterred by what they call an imminent U.S. invasion.

“Yesterday you just saw a small piece of what we’re willing to do to defend the legitimate rights of Venezuela,” Vice President Delcy Rodríguez said on Sunday after the humanitarian convoys were stopped. She addressed Socialist Party supporters who responded with chants of “they won’t enter.”

Mr. Guaidó, a 35-year-old lawmaker, was named in January by the National Assembly to take over an interim presidency after Mr. Maduro’s re-election in May 2018 was marred by fraud allegations. His opposition coalition seeks to organize free and fair elections, which Mr. Maduro has rejected as a coup attempt.

Mr. Guaidó attended Monday’s meetings in Colombia’s capital after leaving Venezuela on foot Saturday in violation of a travel ban recently ordered by Supreme Court magistrates allied with Mr. Maduro. Mr. Guaidó said he planned to fly back directly to Caracas “as any president would.” But speculation swirled over whether the Maduro regime may use his travel as a pretext to arrest him or prevent him from returning.

“A free and defiant Guaidó is an open challenge to the regime’s authority,” J.P. Morgan analyst Ben Ramsey wrote in a report. “But Guaidó is by far the most popular politician in the country at this moment, and jailing him could risk an uncontrollable backlash.”

Late Monday, Univision anchor Jorge Ramos said he and his team were detained for about two hours and their equipment confiscated at the Miraflores presidential palace because Mr. Maduro didn’t like the questions posed during the interview.

After their release Mr. Ramos told Univision Venezuelan security officials seized the crew´s TV equipment, memory cards that recorded the interview and personal items such as cellular phones. Venezuelan Communications Minister Jorge Rodríguez said on Twitter the country’s government ¨won’t engage in cheap shows.¨

Write to Kejal Vyas at kejal.vyas@wsj.com and Ryan Dube at ryan.dube@dowjones.com