Seven former U.S. ambassadors to Ukraine on Tuesday condemned efforts to use the country as a vehicle to “sow division” during the 2020 presidential election campaign.

The letter, which appeared on the website of the Atlantic Council, did not specify what prompted concern among the former ambassadors. But John Herbst, the U.S. envoy to Kyiv from 2003 to 2006 and now director of the think tank’s Eurasia Center, said it was motivated by leaked recordings of years-old phone conversations between then-Vice President Joe Biden and Petro Poroshenko, Ukraine’s president at the time.

The heavily edited tapes were released this month by a Ukrainian lawmaker associated with Rudolph W. Giuliani, President Trump’s personal lawyer.

The recordings, which offered little new insight into Biden’s actions in Ukraine, show that Biden — as he has publicly acknowledged — linked U.S. loan guarantees for Ukraine to the removal of a prosecutor general in 2015. But the tapes allowed Trump’s allies to resurrect allegations against the presumptive Democratic nominee.

“We have worked over the years to build and strengthen the US-Ukrainian strategic partnership established in 1996,” the diplomats, who served during Republican and Democratic administrations, said in the letter.

“We thus are disheartened by efforts to inject Ukraine into America’s domestic politics as the 2020 US presidential election approaches. Those efforts advance a false and toxic narrative, one with no basis in the reality of US-Ukraine relations, in order to weaken the relationship between the United States and Ukraine and sow division within our two countries.”

Herbst said the release of the tapes was probably linked to pro-Russian interests and could undermine U.S. efforts to root out rampant corruption in Ukraine and institute sweeping reforms for good governance.

“This is a ploy by various vested interests,” he said. “The vested interests are, on one hand, the Kremlin, Kremlin-friendly Ukrainians and corrupt interests in Ukraine that realize the sorts of things those tapes describe in distorted and sensationalist fashion is bad for them. Because all the vested interests do not want a Ukraine that reforms.”

The signatories include Marie Yovanovitch, who was forced out of her post last year after Giuliani and his associates accused her of being disloyal to Trump, and William Taylor, a retired former ambassador who was asked to replace her.

The United States has had nine Senate-confirmed ambassadors to Ukraine, a former Soviet republic since it declared independence in 1991. Only one living former ambassador did not sign the letter: Geoffrey Pyatt, a veteran diplomat who preceded Yovanovitch and is currently the U.S. ambassador to Greece. William Green Miller, who served as ambassador under Bill Clinton, died last year.

Since Yovanovitch was abruptly called home a year ago, four diplomats, including Taylor, have headed embassy operations on a temporary basis.

Yovanovitch and Taylor were both witnesses last year during the congressional inquiry that led to President Trump’s impeachment in the House before his acquittal in the Senate. The inquiry focused on whether an understood quid pro quo had taken place between Trump and Ukrainian leader Volodymyr Zelensky.

In a phone call between the two, Trump suggested he would unblock military aid and invite Zelensky to the White House if Ukraine committed to investigate the involvement of Biden’s son Hunter in a Ukrainian gas company where he sat on the board, as well as the alleged Ukrainian interference in the 2016 election.

Yovanovitch told the intelligence investigators that Giuliani had bought into fabricated stories disseminated by allies of Trump claiming she had criticized the president and was blocking corruption probes into the debunked allegations that Ukraine had helped Hillary Clinton during the 2016 election. The ouster of Yovanovitch allowed those allies to push for the investigations.

Taylor testified that it was his understanding that there was a clear quid pro quo offered to Zelensky by Trump allies.

Ukraine had largely faded as an issue in the run-up to the November election, as attention turned to the coronavirus pandemic. But it reemerged last week when Andriy Derkach, an independent member of Ukraine’s parliament who previously aligned with a pro-Russian faction, released the edited snippets of the phone conversations between Biden and Poroshenko.

The recordings have caused a sensation in Ukraine, where Zelensky has called for an investigation into their release. The resulting political turmoil there was what was intended, Herbst said.

“The one thing corrupt interests in Ukraine want from this is to say the dynamic of U.S.-Ukrainian relations over the past six years, where we exhorted them to do the right things with reform, is undercut,” he said. “Because these guys don’t want reform to take place.”