Ukrainian Interior Minister Arsen Avakov warned U.S. diplomats about Rudy Giuliani's partnership with an embattled Ukrainian prosecutor, key officials told House investigators. Avakov, 54, sounded the alarm about then-Ukrainian Prosecutor General Yuri Lutsenko, whose January meeting with Giuliani in New York helped launch the impeachment efforts against President Trump.

“[Avakov] was very concerned, and told me I really needed to watch my back,” former Ambassador Marie Yovanovitch said during her Oct. 11 impeachment deposition.

“He thought Lutsenko was a fool to have made a private trip and to have done what he did,” George Kent, a top official in the State Department’s European Affairs Bureau, testified Oct. 15.

The diplomats' testimony reveals a rift between two Ukrainian officials widely perceived as partners in the corruption that doomed outgoing President Petro Poroshenko’s reelection bid in April. Ukrainian President Volodymyr Zelensky, who pulled off the upset by pledging to "defeat corruption," dismissed Lutsenko but kept Avakov, who has been termed one of Ukraine's "young oligarchs."

“Avakov is effectively the J. Edgar Hoover of Ukraine,” U.S.-based Central European policy specialist who is active in Ukrainian issues told the Washington Examiner. "The general rumor in Kyiv is that Zelensky is keeping him on because he simply knows too much, about too many people, and you've gotta have him on your side.”

“Avakov is a very pragmatic man,” Yovanovitch testified. “He’s looking for partnerships.”

Avakov has reaped contempt from anti-corruption activists. “[Avakov] is a bastard,” Daria Kaleniuk, the co-founder of Ukraine’s Anti-Corruption Action Center, tweeted in August. “Minister of dumped criminal cases, failed reform and un-investigated murders of activists.”

But Avakov also “likes to keep lines of communication open to all sides,” said Kent, the deputy chief of mission at the U.S. embassy in Kyiv from 2016 to 2018. “Mr. Avakov is a very well-informed person." For example, he tipped Kent — who uses WhatsApp — that Israeli cyber-sleuths had cracked the supposedly secure Facebook-owned messaging platform.

In February, Avakov told Yovanovitch and Kent that Giuliani was working with Lutsenko to find evidence implicating former Vice President Joe Biden in a corruption scandal. The Ukrainian official believed that if he complied with Giuliani, he would alienate congressional Democrats — an unacceptable risk for a government that depends on bipartisan U.S. support in the war against Russia.

“He thought it was very dangerous,” Yovanovitch told lawmakers. "To start kind of getting into U.S. politics, into U.S. domestic politics, was a dangerous place for Ukraine to be.”

Yovanovitch dismissed the idea that Avakov was motivated by hostility to Trump, whom he insulted during the 2016 election cycle. “If the president of the United States is DonaId Trump, he's going to work with Donald Trump,” she told lawmakers. “If it is you, he's going to work with you, and he's going to find partnerships and ways to make that work.”

But Zelensky shouldn’t mistake his top law enforcement official for a simple patriot. “I think he was pro-Avakov,” Yovanovitch said.