People cast their votes at in Springdale, Md., in 2016. (Sarah L. Voisin/The Washington Post)

Stephanie Murphy, a Democrat, represents Florida’s 7th Congressional District in the House of Representatives.

In May, other members of Florida’s congressional delegation and I were briefed for 90 minutes in the U.S. Capitol by officials from the FBI and the Department of Homeland Security regarding Russia’s interference in the 2016 election. I sought the briefing after then-special counsel Robert S. Mueller III’s report showed Russia had probed and even pierced election networks in Florida, among the most closely contested states in U.S. politics. Although our briefers supplied new details, much remained unknown. What I do know, I can’t talk about. Why that’s the case is itself a mystery.

The Mueller report noted that Moscow’s meddling involved three lines of effort, and Florida was a target of each. First, a Russian entity conducted a social media campaign to sow discord and help then-candidate Donald Trump, including by organizing pro-Trump rallies in Florida. Second, a Russian intelligence agency — the GRU — hacked computer accounts connected to Hillary Clinton’s campaign. As part of this effort, it published Florida-related data stolen from House Democrats’ campaign arm.

Finally, Mueller reported, the GRU sought to infiltrate computer networks involved in the administration of elections, which could enable Russia to alter voter registration databases or perhaps vote tabulation systems. That would be tantamount to an act of war, with malware rather than missiles as the weapon of choice. While Russian cyber actors cast a wide net, Florida’s county-based election supervisors were a focal point.

The fact that Florida’s election infrastructure was specifically — and successfully — targeted wasn’t made public until about three years after the fact, when a single sentence deep in the Mueller report revealed Russia had breached “at least one” county in the state. Along with my Republican colleague from Florida, Michael Waltz, I asked federal law enforcement officials to brief the state’s congressional delegation. Waltz and I both have national security backgrounds, and we wanted to better understand this threat to our country and state.

At the briefing, we were astonished to discover that, in fact, two Florida counties had been penetrated. Although it appears the Russians were in a position to alter voter data in these counties, there is no evidence to indicate they did so. We were told the counties’ names but were barred by our briefers from disclosing them to the public. A subsequent report by the Republican-led Senate Intelligence Committee, which refers to targeted states by number, has deepened the mystery. The heavily redacted discussion of “State 2” — which appears to be Florida — now suggests four counties might have been compromised. Waltz and I have requested another briefing to clarify. Presumably, we will again be prohibited from sharing what we learn with our constituents.

It’s self-defeating to be given incomplete information and then be required to remain silent about the few facts we do know. If we can’t form a clear picture of past election interference efforts, we won’t learn how best to fend off future attacks.

Why have the details of this foreign attack on our democracy been shrouded in secrecy? For the most part, it’s not the need to protect intelligence sources and methods. Rather, it’s that federal law enforcement agencies view local election officials whose networks were targeted as victims entitled to confidentiality. I believe the victims are the voters, who deserve to know what happened and what their leaders are doing to prevent it from happening again. The half-release of information has one clear side effect; it reduces the public’s faith in our system, which could depress voter turnout. That would please Russian President Vladimir Putin.

Russia will likely use similar tactics in 2020 — to influence whom Americans vote for, to make it harder for registered voters to cast ballots and even to prevent an accurate vote count. While Russia assisted a Republican in 2016, it could aid a Democrat in the future. Moscow’s loyalty is to itself, not any U.S. political party. To defend our democracy, U.S. officials must put America first, a point lost on Senate Majority Leader Mitch McConnell (R-Ky.), who has declined to take up House-passed bills to secure our elections.

I’ve filed a bipartisan bill to require Congress, local officials and affected voters to be swiftly informed if an adversary infiltrates our election system and the federal government believes voter information could be affected. Three years is too long to wait. With 29 electoral college votes and a history of razor-thin election margins, Florida will be the linchpin of any foreign effort to sway next year’s vote. To protect the Sunshine State, and our democracy, more sunshine is needed.