A former U.S. ambassador to Ukraine discussed ties between the two countries and President Donald Trump’s impeachment trial Friday at the Elliott School of International Affairs.

William Taylor, who served as ambassador to Ukraine from 2006 to 2009 and from June 2019 until his departure this January, spoke about the impeachment trial – at which he testified – and the field of diplomacy. About 90 people attended the event, which was moderated by Christopher Kojm, the director of the Elliott School’s Leadership, Ethics and Practice Initiative.

Taylor said his mentor offered him the advice that “if your country asks you to do something, you do it if you can be effective” when he asked him last year whether he should accept the position of chargé d’affaires to Ukraine. Taylor said it was clear that he had the support needed to be effective after talking to Secretary of State Mike Pompeo, so he decided to take the position.

“I needed to be sure that I was going to be supported in pushing a strong support for Ukraine policy,” he said. “I was a little worried that other considerations might present themselves and a deal could be struck by which we reduce our support for Ukraine, in which case, I told the secretary, I couldn’t support it and I would have to resign.”

Taylor said diplomacy and foreign service are “honorable and important” professions, adding that diplomats often do not get credit for the work they do in the same way the military does.

“It’s important to think about where you can make the biggest contribution,” he said.

Taylor said that while in office, policy regarding Ukraine was made in two ways: the “regular channel,” which encompasses formal policy-making processes, and the “irregular channel.” He said his Congressional testimony during impeachment uncovered details about the irregular channel, like how Rudy Giuliani, the president’s “private lawyer,” tried to alter a part of U.S. policy toward Ukraine.

“In the end, the regular channel prevailed and the regular channel reasserted itself,” Taylor said.

He added that in hindsight, he should have figured out “more quickly” that people using the irregular channel were manipulating a “small part” of U.S. policy toward Ukraine.

“The bottom line is that the regular channel is the institutional conscience of the U.S. government, the institution that forms U.S. policy,” he said. “It’s a very important component of our government, and it provides the norms and keeps us on track.”

Taylor said one challenge he has encountered as a diplomat is dealing with corrupt individuals while trying to conduct “honest and straightforward work.”

“Our jobs are to present U.S. views and policy recommendations to the Ukrainian people, but also to listen to them and to understand the good ones and the bad ones, the corrupt and the not-corrupt,” he said. “That balance is hard to strike, it’s a tricky question.”

Taylor said one tool to combat usage of the irregular channel to shape policy is the reliance on the chain of command. He cited as an example the actions of Alexander Vindman, a former director for European Affairs for the National Security Council who spoke to his superior after listening in to a phone call in which President Trump asked Ukrainian President Volodymyr Zelensky to investigate former Vice President Joe Biden.

“It can be self-correcting,” he said. “This institution, that has all of these checks and balances, sometimes to our frustration, can be supportive.”