Prosecutors in Colombia open a probe into an alleged plot to overthrow President Petro as ties sharply deteriorate.

The United States and Colombia have called home their respective top diplomats in an acceleration of worsening ties, against the backdrop of an alleged plot against Colombia’s left-wing leader.

Washington, DC went first, recalling its charge d’affaires John McNamara on Thursday, “following baseless and reprehensible statements from the highest levels of the government of Colombia,” State Department spokesperson Tammy Bruce said, without giving specifics.

In addition to McNamara’s recall, Bruce said the United States “is pursuing other measures to make clear our deep concern over the current state of our bilateral relationship”, without further details.

Within hours, Colombia’s President Gustavo Petro announced he was calling home his top diplomat in Washington, DC, in response.

Ambassador Daniel Garcia-Pena “must come to inform us of the development of the bilateral agenda,” Petro wrote on X, such as tapping South America’s “great potential for clean energy” and the fight against “drug lords and their international finances”.

The diplomatic row came on the heels of the resignation of Colombia’s foreign minister earlier on Thursday – the latest top-ranking official to exit Petro’s government.

“In recent days, decisions have been made that I do not agree with and that, out of personal integrity and institutional respect, I cannot support,” Laura Sarabia, who was also Petro’s former chief of staff, wrote on X.

Deterioration of ties

Colombia was until recently one of the US’s closest partners in Latin America, with decades of right-wing rule, before bilateral relations sharply deteriorated.

Prosecutors in the South American nation opened an investigation this week into an alleged plot to overthrow Petro with the help of Colombian and American politicians, following the publication by the Spanish daily El Pais of recordings implicating former Foreign Minister Alvaro Leyva.

“This is nothing more than a conspiracy with drug traffickers and apparently, the Colombian and American extreme right,” Petro said on Monday.

During a speech in Bogota on Thursday, Petro said he did not think US Secretary of State Marco Rubio, whom he had previously linked to the alleged overthrow attempt, was “in the midst of a coup d’etat” against his government.

“I don’t believe that a government that has Iran as its enemy and nuclear weapons pointed at it … is going to start fooling around with a coup d’etat” in Colombia, he said.

In late January, the US briefly suspended consular services to retaliate for Petro’s refusal to allow US military planes to return Colombian refugees and migrants to their homeland.

Petro accused the US of treating them like criminals, placing them in shackles and handcuffs.

The two countries issued threats and counter-threats of crippling trade tariffs of up to 50 percent.

A backroom diplomatic deal involving the deployment of Colombian air force planes to collect the refugees and migrants averted a looming trade war at the eleventh hour.

Al Jazeera’s Alessandro Rampietti, reporting from Bogota, said the first crisis between the two countries over the deportation of migrants was resolved quickly in January.

“The current situation is obviously very worrisome as it is unclear what will happen in this case,” he said.

“But it shows that ties that were taken for granted might now be unravelling,” Rampietti added.

Colombia’s left-wing government also recently refused a US request to extradite two prominent rebel leaders wanted by Washington, DC, for alleged drug trafficking.

Last month, Colombia was rattled by bombing attacks in Cali in the southwest of the country that killed seven people, and the attempted assassination of a conservative opposition senator and presidential hopeful, Miguel Uribe Turbay, at a campaign rally in Bogota. The eruption of violence raised fears of a return to the darker days of previous decades, of assassinations and bombings.