Sen. Amy Klobuchar wants an updated classified briefing on Russian efforts to hack U.S. election systems, given the leak of an apparent NSA report detailing a cyber assault targeting local election officials.

"While I understand that certain information must remain classified, protecting our election infrastructure requires information-sharing with the federal, state, and local officials who are responsible for overseeing and administering elections," Klobuchar, the top Democrat on the Senate Rules Committee, wrote today in a letter to national security adviser H.R. McMaster.

Klobuchar noted that the NSA document, published Monday by The Intercept, "is deeply concerning and goes beyond" the intelligence community's previous reports on Moscow's digital meddling, which described the efforts mostly in broad strokes.

Monday's disclosure set off alarm bells on Capitol Hill.

“It's clear they were trying to get into voter files,” said Missouri Sen. Claire McCaskill, the Senate Homeland Security Committee’s top Democrat, during a hearing today. “I don’t think they were going there just to hang out.”

Homeland Security Secretary John Kelly said during the hearing that he would be willing to discuss the topic in a classified setting.

Klobuchar has previously pressed the administration for more details about how it was responding to Russia's apparent hacking campaign. In February, she lead a group of 26 Senate Democrats in a letter asking the U.S. Election Assistance Commission what measures the panel is taking to protect future elections from foreign hackers.

In addition to a closed-door briefing, Klobuchar also urged McMaster to "consider making information that could be helpful to protecting critical infrastructure publicly available immediately."