Sergey Kislyak, Russia's ambassador to the U.S., has stayed publicly silent and out of sight as the Crimea crisis has worsened. (Cliff Owen/AP)

There are many hard jobs in the world of diplomacy, but perhaps none is harder right now than that of Russia’s ambassador to Washington.

Sergey Kislyak is one of Russia’s most direct links to the Obama administration at a time when a war of words over Crimea has plunged relations between Washington and Moscow to their lowest point since the collapse of the Soviet Union.

But Kislyak, 63, has remained publicly silent and out of sight over the past two weeks as the crisis has worsened.

No round of television appearances hotly defending Russia’s interests. No quiet, not-for-attribution invitations to American reporters to present the Russian case, as is the practice of some embassies in town. Kislyak doesn’t tweet, and he isn’t on Facebook.

The Russian Embassy did not respond to e-mails and phone calls requesting an interview or comment for this story.

But as the Obama administration slapped the most far-reaching sanctions on Russia in decades, Kislyak was at the hulking Russian Embassy on Wisconsin Avenue. The Ukrainian-born Kislyak has been uncharacteristically out of sight, U.S. officials said, except for a lunch meeting with the top U.S. official for Europe on Wednesday, a day before President Obama announced economic and travel sanctions on some of Russian President Vladi­mir Putin’s closest advisers and oldest friends.

Current and former U.S. officials who know Kislyak describe him as a smart, genial technocrat with moderate influence in Moscow. He is not part of Putin’s inner cadre and has spent much of his professional career abroad.

“He represents the interests and positions of his government very well,” said Michael McFaul, who was Kislyak’s counterpart as U.S. ambassador to Russia until a few weeks ago. McFaul dealt with Kislyak most closely, however, when McFaul was the top Russia expert on the White House National Security Council.

“He’s a very active ambassador in the positive sense,” McFaul said. “He was constantly trying to meet with me” and with U.S. officials across many agencies, McFaul said.

Kislyak is direct, well prepared and persistent in meetings, current and former U.S. officials said. Although not overtly ideological, he sticks to the Russian government line on all issues, said several people who have dealt with him.

Although Moscow might consider recalling Kislyak in a symbolic protest of U.S. actions, it has not done so. The United States would not be able to reciprocate because the post of U.S. ambassador to Russia is vacant.

Kislyak speaks excellent English. He served at Moscow’s missions in New York and Washington before returning here as ambassador, and he was Moscow’s first representative to NATO, the Atlantic military alliance originally formed as a bulwark to the Soviet Union.

He has seen U.S.-Russian relations freeze before. He began his posting as ambassador in September 2008, just a month after the United States and Russia clashed over breakaway regions of Georgia.

“Most probably, it was the lowest point in our relations after the end of the Cold War,” Kislyak told a U.S. audience in 2010.

The United States “seemed to be judging us instinctively in a way that was less than friendly,” Kislyak told the World Affairs Council of Northern California. “One of the biggest problems in our relations is that we sometimes look at each other through old stereotypes.”

Kislyak counts as a formative period several years in Washington working on arms-control issues during the Reagan administration. Immediately before his current posting in Washington, Kislyak was Russia’s deputy foreign minister and an occasional stand-in for Foreign Minister Sergei Lavrov.

In some ways, he is the Russian opposite of the crisply tailored, acerbic Lavrov. Where Lavrov loves the limelight and often uses it to show up American officials, Kislyak is quieter, a bit rumpled, and does not seek publicity.

He is an old-school diplomat, preferring one-on-one lunches and intimate dinner parties to the public eye.

Although he has made several appearances at think tanks and in academic settings since taking over in 2008, news interviews are rare.

On Jan. 31, however, Kislyak spoke to CNN, before the then-simmering Ukraine crisis boiled over.

The Winter Olympics in Sochi would be safe despite U.S. fears of terrorism, he told host Candy Crowley. If Kislyak was irked by the suggestion that Russia was tempting fate by holding the Games near the restive Caucasus region, he masked it.

“The phenomenon of terrorism is global in nature,” Kislyak said evenly. “So wherever you are, you might become a target of a terrorist. We do not take it lightly.”

The next week, addressing a World Affairs Council audience in Charlotte, Kislyak had apparently tired of questions about whether Russia was up to the task of hosting the Games. “Yes, the Olympics will be safe,” he said tersely.

Also in that address, Kislyak said he hoped that the next generation would regard the period of difficult relations between Russia and the United States as “something from the history manual,” the Charlotte Observer reported.

Like the confrontation over Russia’s annexation of the Crimea region from Ukraine, the 2008 Georgia conflict set back U.S.-Russian attempts to forge a post-Cold War relationship founded on cooperation on arms control and shared economic and counterterrorism goals.

Both episodes expose how close to the surface the old Cold War animosity can be — and how reflexive the response. In the 2010 speech to the World Affairs Council, Kislyak questioned the reason for further confrontation.

“There is no basis,” he said, “for the resurrection of the Cold War.”

Julie Tate contributed to this report.