Venezuelan authorities have set up barriers to block the entry of donated food and medicine from neighboring Colombia amid an escalating political dispute over humanitarian aid that other countries have rushed toward the embattled country's borders. The self-proclaimed opposition Venezuelan government — which controls no territory or border posts — has called on Venezuelan troops and police to allow the entry of tens of millions of dollars in aid pledged in recent days by the United States, Canada and various European nations.

Vice President Mike Pence arrived in the Colombian capital and headed immediately into a meeting with Colombian President Ivan Duque. Pence will also meet with members of a regional coalition and Venezuelan opposition leader Juan Guaido to discuss the next steps aimed at ousting Maduro.

On Friday, some of Latin America's hottest artists will be playing a benefit concert in Cucuta, Colombia, in hopes of pressuring Venezuelan leader Nicolas Maduro to accept tons of humanitarian aid. The initiative, called Venezuela Aid Live, hopes to raise more than $100 million and is being organized by British billionaire Richard Branson.

Defying orders banning him from leaving Venezuela, opposition leader Juan Guaido made a surprise appearance at the end of star-studded aid concert in neighboring Colombia, joining thousands of other Venezuelans in pressuring President Nicolas Maduro into allowing the delivery of emergency food and medicine. In Venezuela, a much smaller crowd gathered for a rival, three-day "Hands Off Venezuela" festival being organized by Maduro. Even as several million Venezuelans flee the country and those who remain struggle to find basic goods like food and antibiotics, the embattled president claims the relief effort led by Guaido is a U.S. orchestrated ploy to oust him from power.

A U.S.-backed campaign to force President Nicolas Maduro from power met strong resistance Saturday from Venezuelan security forces who fired tear gas on protesters trying to deliver humanitarian aid from Colombia and Brazil, leaving two people dead and some 300 injured. "They burned the aid and fired on their own people," said 39-year-old David Hernandez, who was hit in the forehead with a tear gas canister that left a bloody wound and growing welt. "That's the definition of dictatorship."

Colombian President Ivan Duque on Friday pressed Cuba to arrest 10 peace negotiators from the National Liberation Army — ELN for its Spanish initials — after his government blamed the leftist group for a car bombing against a police academy that left 21 dead and dozens more wounded. Duque revoked a decree suspending arrest orders against leaders of Colombia's last remaining rebel group after authorities claimed that Jose Aldemar Rojas, the man who died carrying out the attack, was an ELN explosives expert. The group has stepped up similar strikes amid stalled peace talks with the conservative government led by Duque, who asked that Cuba arrest and deliver the rebels accused of perpetrating the deadliest attack his country has seen in 15 years.

A U.S.-backed campaign to force President Nicolas Maduro from power met strong resistance Saturday from Venezuelan security forces who fired tear gas on protesters trying to deliver humanitarian aid from Colombia and Brazil, leaving two people dead and some 300 injured. "They burned the aid and fired on their own people," said 39-year-old David Hernandez, who was hit in the forehead with a tear gas canister that left a bloody wound and growing welt. "That's the definition of dictatorship."

In a nation awash with rumors amid a government crisis in which two men have claimed Venezuela's presidency, even the unexpected arrival of a Russian passenger jet can set off a social media frenzy. The Boeing 777 belonging to Russia's Nordwind Airlines arrived Monday night and could still be seen Wednesday on the tarmac at Maiquetia airport outside the capital, its presence sparking unproven claims that President Nicolas Maduro's administration is looking to whisk what's left of the nation's depleted gold reserves out of the country.

The latest on Syria and U.S. military pullout: Syrian state media are reporting that air defense units have responded to "hostile targets" near the capital of Damascus. State TV said in its Friday night report that explosions were clearly heard in Damascus. Israel is widely believed to have been behind a series of airstrikes in Syria that have mainly targeted Iranian and Hezbollah forces fighting alongside the Syrian government.