Insiders hope new leadership will provide a shot in the arm. C.I.A. Director Mike Pompeo, who is expected to be confirmed by the Senate this week to take over the State Department, has expressed support for the G.E.C., testifying before the Senate Foreign Relations Committee earlier this month that he is committed to fighting disinformation. “We’ve had a small role at the Central Intelligence Agency pushing back against it,” he told Senator Rob Portman for a funding commitment. “I know that there’s been lots of talk about the Global Engagement Center. In the event that I’m confirmed, I promise you I will put excellent foreign-service officer, excellent civil-service officers, on the task of developing out that capability use—and using it in a robust way.”

There are, of course, less public government efforts underway to combat disinformation, including within Cyber Command and Special Operations Command. According to the senior State Department official, the State Department contributed $1.3 billion during 2017 to bolster European resistance to Russian interference in the form of support for independent media, civil society, media literacy, and democratic institutions, among other things. “It is easy to criticize what we are trying to do, even though most people have no idea, because much of the work is classified and private,” Goldstein told me. “Listen, we take responsibility for what we are responsible for. It took too long to get the $40 million in, but it is not as if people were sitting around in their offices just waiting for the money to come in. That has just not been the case.”

The problem, according to people familiar with these efforts, is that social media is a relatively new theater of war for the United States—and, potentially, one without any silver bullet. “I still haven’t seen anybody give me a good answer on how to combat disinformation,” said Rick Stengel, who had oversight of the G.E.C. as undersecretary for public diplomacy during the Obama administration. “It’s only been around since the Garden of Eden, and nobody’s ever come up with a good answer against it.” Obama-era staffers were flummoxed in 2014, when the Kremlin escalated so-called “special-war” tactics in Ukraine, manipulating the media to muddy international coverage of its invasion of Crimea. “There was a recognition at the White House that this was different, and that the kind of propaganda . . . that was different from what had been used before,” explained Brett Bruen, a former foreign-service officer who served as the White House director of global engagement from 2013 to 2015. “What was evident to me and to others was that we needed to get to a point where we had more tools that were preconstructed, and ready to deploy when and where they were needed, especially around principal vulnerabilities.”

Yet the Obama administration was caught flat-footed. “There were people who were aware of the extent of Russian disinformation in the periphery, and around the annexation of Crimea and the invasion of Ukraine,” Stengel said. “In fact, the expansion or the creation of the G.E.C. was, in large part, due to that. Senators Portman and [Chris] Murphy were onto this. Their bill was about trying to make the U.S. more robust in responding to Russian disinformation,” he continued. “I was certainly aware of it and created the first counter-Russian disinformation entity at the State Department . . . but I’d be a liar if I told you I thought that the U.S. would be next.”

Indeed, there was a widely held belief that the the U.S. media landscape would be more resistant to Kremlin-backed propaganda, a former high-ranking N.S.C. and State Department official told me. Instead of scrutinizing the war playing out on Twitter and Facebook, government officials in the summer of 2016 were concerned that Russian operatives might seek to physically alter votes, and missed the forest for the trees. “I think we kind of missed fully understanding the social-media landscape and how that could be manipulated or abused,” the former official told me, noting that it wasn’t until after the election that the full picture of Russia’s interference came into focus. “I think there was a certain amount of wishful thinking that we are all subject to—that we live in a society that has been less prone to conspiracy theories and misinformation and so-called ‘fake news’ until recently. In our system, the truth usually rises to the top. Unfortunately, that is no longer the case, and Russia was able to take advantage of that.”

There was also a belief within the administration that Russia wouldn’t dare meddle in a U.S. election. The idea that “they would anticipate that our retaliation would be so strong that it wouldn’t be worth it—the price was too high because we would come at them with everything if they ever attacked our democracy,” Moira Whelan, who served as the deputy assistant secretary for digital strategy at the State Department under Obama, told me. “That was one assumption that, sitting inside the Obama administration, I think I personally made—I think other people made.”

The more terrifying concern now, among some former officials, is that President Trump has little interest in solving the problem—and may even have a personal stake in allowing it to fester. “I think the Obama administration should have been stronger,” the former State Department official told me, offering a neat summation of the dilemma facing the G.E.C. “The Trump administration could hardly be weaker.”

This article has been updated.