Acting Ukraine Ambassador Bill Taylor has emerged as a key witness in the House’s impeachment inquiry. But this week, he made quite a statement in the court of public opinion, in the form of a strikingly topical op-ed.

Taylor has testified, and is expected to do so again publicly on Wednesday, that the Trump administration used irregular foreign policy channels to pressure Ukraine into pursuing President Donald Trump’s political interests.

Though Republicans have defended Trump by arguing he was simply pushing for corruption investigations into Joe Biden and the 2016 U.S. elections, Taylor and others have noted that calling for individual investigations — rather than broad anti-corruption efforts — is the opposite of America’s standard line in Ukraine.

The ambassador seemed to note the irony in his op-ed.

“As in all democracies, including the United States, work remains in Ukraine, especially to strengthen rule of law and to hold accountable those who try to subvert Ukraine’s structures to serve their personal aims, rather than the nation’s interests,” he wrote.

And though Trump’s hostility toward Ukraine has been well-documented — he’s pushed multiple conspiracy theories accusing the country of meddling in the 2016 elections — Taylor’s piece overflowed with talk of binational cooperation.

“The United States stands side by side with the people and government of Ukraine, ready to help Ukraine achieve its goals,” he asserted, adding: “The United States is firmly committed to Ukraine’s success – your success is our success.” Ukrainians working to tackle the country’s problems, he said, “can count on the United States’ committed partnership and support.”

A central question in Trump’s Ukraine scandal is whether the President held up nearly $400 million in aid to Ukraine to pressure them to provide political dirt. Taylor made only glancing reference to the aid.

“The United States continues to provide weapons, training, and equipment to Ukraine’s armed forces,” he said of the nine-figure package Trump released in September after intense bipartisan criticism over the hold.

Elsewhere in the piece, the veteran diplomat’s commentary on Ukrainian politics appeared to describe common criticisms of President Trump’s worst habits.

“It appears to me that Ukrainians want a new Ukraine — a prosperous, democratic Ukraine, where all citizens are held equally accountable under the law, where decisions by judges and MPs are not bought, where oligarchs do not wield influence over political and economic policy,” Taylor wrote.

“They want a new Ukraine where journalists do not face reprisal for honest reporting,” he added, “where businesses know they are investing in a transparent and fair environment and have an impartial court to mediate disputes.”

The acting ambassador will appear for public testimony Wednesday alongside deputy assistant secretary of state George Kent.