THE BURNED OVER DISTRICT

Until Trump confesses or Putin releases his tapes of the meeting we will never know. What we do know is that important intelligence sources close to Putin and the Kremlin have gone silent.

In 2016, American intelligence agencies delivered urgent and explicit warnings about Russia’s intentions to try to tip the American presidential election — and a detailed assessment of the operation afterward — thanks in large part to informants close to President Vladimir V. Putin and in the Kremlin who provided crucial details.

But two years later, the vital Kremlin informants have largely gone silent, leaving the C.I.A. and other spy agencies in the dark about precisely what Mr. Putin’s intentions are for November’s midterm elections, according to American officials familiar with the intelligence.

The officials do not believe the sources have been compromised or killed. Instead, they have concluded they have gone to ground amid more aggressive counterintelligence by Moscow, including efforts to kill spies, like the poisoning in March in Britain of a former Russian intelligence officer that utilized a rare Russian-made nerve agent.

Current and former officials also said the expulsion of American intelligence officers from Moscow has hurt collection efforts. And officials also raised the possibility that the outing of an F.B.I. informant under scrutiny by the House intelligence committee — an examination encouraged by President Trump — has had a chilling effect on intelligence collection.

Technology companies and political campaigns in recent weeks have detected a plethora of political interference efforts originating overseas, including hacks of Republican think tanks and fake liberal grass-roots organizations created on Facebook. Senior intelligence officials, including Dan Coats, the director of national intelligence, have warned that Russians are intent on subverting American democratic institutions.

But American intelligence agencies have not been able to say precisely what are Mr. Putin’s intentions: He could be trying to tilt the midterm elections, simply sow chaos or generally undermine trust in the democratic process.

The officials, seeking to protect methods of collection from Russia, would not provide details about lost sources, but acknowledged the degradation in the information collected from Russia. They spoke on condition of anonymity because they were not authorized to reveal classified information. A spokesman for the C.I.A. declined to comment.

To determine what the Russian government is up to, the United States employs multiple forms of intelligence, including intercepted communications and penetrated computer networks.

The United States continues to intercept Russian communication, and the flow of that intelligence remains strong, said current and former officials. And Russian informants could still meet their C.I.A. handlers outside Russia, further from Moscow’s counterintelligence apparatus.

Because clandestine meetings can take months to set up and complete, a lengthy lag can pass before the C.I.A. realizes a key source has gone silent, according to former officials. It is rare for the agency to discover immediately that informants have eroded or are running scared. Only after several missed meetings might C.I.A. officers and analysts conclude that a source has decided it is too dangerous to pass information.

Espionage is a long game and if Trump helped Putin cut to the end by giving him a list of sources in the Kremlin, it will still be a long time before that can be confirmed. Until then we can only hope the Intelligence Community never let Trump anywhere near that vital information.