Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

President Nicolás Maduro of Venezuela cut off diplomatic ties with neighbor Colombia on Saturday after that nation was used as a staging ground for a U.S.-backed aid effort that he has vowed to block.

Opposition leader Juan Guaidó, who is recognized by President Trump as Venezuela's legitimate leader, was in Colombia for a concert organized by billionaire Richard Branson.

"We can't keep putting up with Colombian territory being used for attacks against Venezuela," Maduro said at a rally. "For that reason I’ve decided to sever all ties with the fascist government of Colombia. All consul employees should leave within 24 hours. Out! Get out. Enough is enough."

Colombia's Foreign Ministry responded in a statement that the nation "does not recognize the legitimacy of the usurper Maduro" and instead backs Guaidó.

"Colombia has always acted in a humanitarian and peaceful way and will continue to do so in order to help create the conditions that will give rise to democracy and freedom in Venezuela once again," the statement reads.

Maduro is refusing food and medical supplies based on his belief that it will be used by the United States as a means to curry favor with troops and overthrow him.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Late Saturday, Secretary of State Mike Pompeo tweeted that the United States would respond to Maduro's recalcitrance. "The U.S. will take action against those who oppose the peaceful restoration of democracy in #Venezuela," he said.

The U.S. will take action against those who oppose the peaceful restoration of democracy in #Venezuela. Now is the time to act in support of the needs of the desperate Venezuelan people. We stand in solidarity with those continuing their struggle for freedom. #EstamosUnidosVE pic.twitter.com/XfLEsyT6Rj — Secretary Pompeo (@SecPompeo) February 24, 2019

Guaidó said Saturday that he planned to meet U.S. Vice President Mike Pence in Bogotá on Monday during an emergency meeting of Latin American foreign ministers.

Guaido also tweeted that the day's events had obliged him to "propose in a formal manner to the international community that we keep all options open to liberate this country which struggles and will keep on struggling."

The opposition leader did back off his earlier requests for supporters to breach the border with aid, but he continued an appeal to Venezuelan troops to defect.

"How many of you national guardsmen have a sick mother?" he said. "How many have kids in school without food?"

In a subsequent statement Pompeo also urged troops still loyal to Maduro to switch sides.

"Now is the time to act in support of democracy, and respond to the needs of the desperate Venezuelan people," he said. "The United States will take action against and hold accountable those who oppose the peaceful restoration of democracy in Venezuela."

U.S. Sen. Marco Rubio, R-Florida, warned Maduro on Saturday that violence at the border opened the possibility of intervention.

"After discussions tonight with several regional leaders it is now clear that the grave crimes committed today by the Maduro regime have opened the door to various potential multilateral actions not on the table just 24 hours ago," he tweeted.

Rubio is a member of the Senate's Committee on Foreign Relations and has advised the Trump administration on Venezuela.

Last month Trump declared that he backs Guaidó, sparking increased tension with the Maduro regime and inspiring the Venezuelan leader to cut diplomatic ties with the United States.

Trucks loaded with supplies intended for Venezuela, where food is so scarce some citizens are calling their weight loss part of a "Maduro diet," were set ablaze Saturday as they reached the Francisco De Paula Santander International Bridge at the Venezuela-Colombia border Saturday, according to drone footage.

Two trucks were repelled at the border by troops loyal to Maduro. They returned to warehouses in Colombia.

The Venezuelan military used tear gas and rubber pellets against volunteers and opposition supporters attempting to help transport aid across the border. Injuries were reported, according to Telemundo.