As a U.S. diplomat, Marie Yovanovitch braved gunfire in Moscow, the violence of Somalia’s civil war, an attack on the U.S. Embassy in Uzbekistan and 10 trips to the front line of Ukraine’s war with Russia.

But her greatest service to country may well have been what Yovanovitch did on Friday before the House Intelligence Committee. All Americans — however they feel about impeachment — should care deeply about her warning.

She used her moment in the spotlight at the impeachment inquiry to make a passionate plea for American diplomacy, which is being destroyed under the Trump administration, with dire consequences for U.S. influence and security.

The former U.S. ambassador to Ukraine recited her well-documented account of how a corrupt Ukrainian official who had been targeted by Yovanovitch’s anti-corruption efforts worked with Trump lawyer Rudy Giuliani and two cronies now under U.S. indictment to defame Yovanovitch and have President Trump remove her from her post.

“How could our system fail like this?” she asked. “How is it that foreign corrupt interests could manipulate our government? Which country’s interests are served when the very corrupt behavior we have been criticizing is allowed to prevail?”

She continued: “Such conduct undermines the U.S., exposes our friends and widens the playing field for autocrats like President Putin. Our leadership depends on the power of our example and the consistency of our purpose. Both have now been opened to question.”

Even the committee’s Republicans, who spent much of the day raising parliamentary objections, listened attentively to the slight figure before them. She spoke softly and had a blanket in her lap in the cold room, but her words were fiery.

“This is about far, far more than me or a couple of individuals,” she said. Yovanovitch declared “a crisis in the State Department as the policy process is visibly unraveling. . . . The crisis has moved from the impact on individuals to an impact on the institution itself. The State Department is being hollowed out from within at a competitive and complex time on the world stage.”

Hollowed out from within: This is one of Trump’s most damaging legacies. As the president debases public service and undermines U.S. officials in front of allies and adversaries, skilled public servants are leaving their jobs and competent replacements are not to be found. It isn’t just Foggy Bottom; Trump has similarly vilified the Justice Department, the FBI and CIA, politicized the military and portrayed all civil servants as the enemy. In the process, he is disabling not a so-called deep state but the United States — at home and abroad — for years to come.

Trump, as though to prove Yovanovitch’s case, attacked her on Twitter as she testified. “Everywhere Marie Yovanovitch went turned bad,” he wrote. “She started off in Somalia, how did that go?”

It was typical Trumpian absurdity — she’s responsible for Somalia’s war? — and thuggish witness intimidation, and it drew a perfect contrast for all to see: A woman who served Democratic and Republican administrations alike for 33 years with “no agenda other than to pursue our stated foreign policy goals,” as she put it, and a president who has no agenda other than self-interest.

Republicans shied from Trump’s character assassination of Yovanovitch in favor of a subtler belittling. “I’m not exactly sure what the ambassador is doing here today,” said Rep. Devin Nunes (Calif.), the committee’s ranking Republican, suggesting that Yovanovitch’s “issues with employment disagreements with the administration” should be directed to a “human resources” subcommittee.

His pettiness was all the more disgraceful because of the power of Yovanovitch’s message. The daughter of refugees from the Soviet Union and Nazi Germany condemned the “degradation of the Foreign Service” and “the failure of State Department leadership to push back as foreign and corrupt interests apparently hijacked our Ukraine policy” — and the administration’s refusal to defend diplomats who risk their lives for country.

“We are the 52 Americans” held captive in Iran, she said. “We are the dozens of Americans” injured in attacks at their posts in Cuba and China. “And we are Ambassador Chris Stevens, Sean Patrick Smith, Ty Woods and Glen Doherty, people rightly called heroes for their ultimate sacrifice to this nation’s foreign policy interests in Libya, eight years ago.”

Republicans, during their endless Benghazi hearings, professed to care about the treatment of U.S. diplomats. Now, they say nothing as Trump abuses them.

Yovanovitch reminded the politicians that diplomats still believe politics stops at the water’s edge. “We answer the call to duty to advance and protect the interests of the United States,” she testified. “We take our oath of office seriously, the same oath that each one of you take: ‘to support and defend the Constitution of the United States against all enemies, foreign and domestic . . .’ ”

Yovanovitch honored her oath. It’s time some elected officials did the same.

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