U.S. officials have informed Sen. Bernie Sanders that Russia is actively trying to support his campaign for the Democratic nomination as part of Moscow’s broader efforts to interfere in the 2020 election, according to two people familiar with the matter…

The classified FBI briefing wasn’t of the type routinely given to presidential campaigns about election security, those people said. It was given in reaction to intelligence considered compelling enough that Mr. Sanders needed to be alerted, one of the people said. But the intelligence suggested that the Russian effort to bolster Mr. Sanders hasn’t approached the scale or scope of operations to support Mr. Trump’s campaign in 2016, the person said…

Sen. Elizabeth Warren, one of Mr. Sanders’s rivals for the Democratic nomination, told reporters Friday she hadn’t received a similar briefing.

“I believe that we need as much transparency as possible on any Russian interference,” she said. “Understand, this is about disinformation and the way to fight disinformation is to call it out, show what it is, and give everyone full information as quickly as possible. Otherwise, the Russians continue to have too much influence over our campaign, and this is how we fight against that.”