MOSCOW » In the annals of U.S. diplomacy, few honeymoons have been shorter than the one granted to Michael A. McFaul, who arrived in Russia on Jan. 14 as the new U.S. ambassador.

Toward the end of his second full day on the job, a commentator on state-controlled Channel 1 suggested during a prime-time newscast that McFaul was sent to Moscow to foment revolution. A columnist for the newspaper Izvestia chimed in the next day, saying his appointment marked a return to the 18th century, when "an ambassador’s participation in intrigues and court conspiracies was ordinary business."

McFaul, 48, has arrived in a city churning with conjecture and paranoia, as the Kremlin tries to portray a wave of anti-government protest as a project driven by the U.S. If the blast of venom that greeted McFaul was intended as a warning to maintain a low profile in his new role, he seems unlikely to comply. At the end of his first week, he was exuberant, saying his goal is to "destroy Cold War stereotypes," especially "gross statements" about the United States’ intentions in Russia.

"I know I’m just going to go in full force, I’ve got nothing to hide, and we feel very confident in our policy and in selling our policy," said McFaul, a native of Bozeman, Mont., who spent much of his career in academia. He does not need to fret over his next diplomatic posting, he added, because there will not be one.

"I ain’t going nowhere else," he said, with a big smile. "This is it. I am not a career diplomat. And so I am here to do that in a very, very aggressive way."

McFaul is an unusual choice for ambassador to Moscow, even more so than it appeared when the decision was announced in May 2011.

At that point, he was seen primarily as President Barack Obama’s top Russia adviser and the architect of the so-called reset policy, which brought an end to the deep freeze of the late years of George W. Bush’s administration and invited Russia to cooperate on projects like nuclear nonproliferation.

From the Kremlin’s viewpoint, it was a positive sign that McFaul, only the second non-career diplomat to get the post in 30 years, is a member of Obama’s inner circle, reflecting the priority the president puts on Russia.

Nine months later, the Kremlin has been shaken by protests challenging Prime Minister Vladimir V. Putin, who hopes to win a third term as president in five weeks. Amid repeated accusations that the State Department had mobilized the protesters, attention swung to McFaul’s earlier career — as a political scientist who specialized in revolution and democracy-building.

In a 2007 article in The American Interest magazine, he wrote that "even while working closely with Putin on matters of mutual interest, Western leaders must recommit to the objective of creating the conditions for a democratic leader to emerge in the long term."

McFaul said his academic work has at times complicated his work as Obama’s Russia strategist, and he emphasized that he is in Russia to "execute and deepen and strengthen" the reset.

"There have always been rumors because I have written about certain subjects that that is what I am coming to do here," he said. "That’s crazy. Just because you write about cancer doesn’t mean you advocate cancer. I’m a social scientist. I’ve written about democratization, but that’s my previous life.

"The most important thing for people to understand is that I’ve been a government official for three years," he said. "Every step of the way, on every major issue to deal with this country, I’ve been intimately involved in the reset."

It took almost no time for McFaul to slam into the forces awaiting him: the gimlet-eyed scrutiny accorded to U.S. ambassadors in Moscow, the archaic codes of diplomatic life, and the blasts of invective that issue from pro-Kremlin television. The occasion was a meeting McFaul attended on his second day of work, after devoting his first to talks with government officials.

Several opposition figures arrived at the U.S. Embassy on that Tuesday to meet with a visiting U.S. official, Deputy Secretary of State William J. Burns. Burns’ meetings had been arranged before McFaul’s arrival date was set, and the two men debated whether McFaul should attend, since protocol required him to first present his credentials to the Ministry of Foreign Affairs. McFaul did so on Monday, and then attended the meetings, which are standard for high-level visits, he said.

That night, a Channel 1 newscast reported the meetings as "the first steps of the new U.S. ambassador to Russia." A camera crew peppered the visitors with questions as they waited to be admitted to the embassy, and the clip was titled, "Receiving Instructions at the United States Embassy." An accompanying commentary singled out a book by McFaul, "Russia’s Unfinished Revolution," and asked, "Is it possible that Mr. McFaul came to Russia to work in his specialty? That is, to finish the revolution?"

Over the weekend, two more broadcasts focused on the episode. A talk show host, Alexei K. Pushkov, who is also chairman of the parliamentary foreign affairs committee, warned that McFaul might lose the ability to meet with high-level officials if he was seen as allying himself with the opposition. Russian leaders are acutely sensitive to any indication that the U.S. has taken a side in the coming elections, he said, though "there is no desire in Moscow to have a major crisis with the United States."

"A lot will depend on Obama, whether Obama gives the impression that America doesn’t want Vladimir Putin in office for a third term," he said. "If Obama shows this is not the case, maybe we will somehow manage to reset the reset. If there are demonstrations that this impression is the right one, then I don’t think we will see a very nice future."

McFaul found out about the original report when Alexei Navalny, a blogger and opposition leader, sent him the clip via his Twitter feed. The ambassador shot off a pointed comment instantly, via Twitter, noting that he had received a warm welcome from top officials over eight hours on Monday, suggesting there were splits within the Russian government on relations with Washington.

That response offers a taste of what McFaul means when he says he intends to be a "21st-century ambassador," using blogs and social media to directly communicate with Russians. This is in itself a departure from tradition, in which U.S. diplomats would negotiate with Soviet and Russian officials for slivers of airtime.

"Not only is my style going to be different, but the methods I’m going to use might also be different," McFaul said. "I have a lot of things from my past that may be constraining, but one thing I know how to do, or I think I know how to do, is get up in front of 500 20-year-olds."

McFaul’s open, passionate manner will serve U.S. interests, said Sergei A. Markov, an old friend and co-author. Markov, now a Putin loyalist and member of United Russia, recalls his arguments with McFaul as some of the loudest of his life.

"Diplomats are cold and McFaul is warm, that is the difference," he said. "A spirited person representing America is always good for America. America is a very spirited country."

There are risks, too. Some in the opposition cringed at the footage from outside the embassy, saying it gave credence to the government’s arguments about U.S. interference. And McFaul’s job will require him to build ties with all parts of Russian society — including its leaders, some of whom genuinely believe that the United States is working to undermine Putin, said Dmitry V. Trenin, director of the Carnegie Moscow Center and an old friend.

"He will be under tremendous pressure," Trenin said. "He has extremely good assets that he could use to become perhaps the best American ambassador to this country — to the Russian empire or the Soviet Union or the Russian Federation. Or he can be a disaster. The difference in how you handle yourself can be very slight."