With all the noise over “collusion” and “obstruction” and, most recently, “the memo,” let’s not forget the main purpose of Special Counsel Robert Mueller’s investigation. The reason we’re having this investigation isn’t just about President Donald Trump; it’s about President Vladimir Putin.

Robert Mueller was appointed “to ensure a full and thorough investigation of the Russian government’s efforts to interfere in the 2016 presidential election.” This appointment came after the Office of the Director of National Intelligence reported that the U.S. intelligence agencies — consisting of military and civilian intelligence agencies — had concluded "with high confidence" that the Russian government interfered in the election by:

Hacking into the Democratic National Committee’s and Hillary Clinton campaign’s emails and leaking them to WikiLeaks.

Disseminating fake news about Ms. Clinton on social media.

Trying to hack into election systems and databases of multiple U.S. states.

The intelligence community recognized the Russian government’s imprint on these techniques because the Russians had used them before in attempts to influence other foreign elections. The FBI began several related investigations into Russian election influence during the summer of 2016, which were consolidated into Mr. Mueller’s investigation.

Free, fair and fully informed elections are the foundation of our democratic republic. The Founding Fathers affirmed that government belongs to the people, and that all government power is granted by the people to those they either select to lead the government or who are appointed under that authority. Elections are the method the founders established by which the people could delegate to specific individuals the legislative and executive powers that were authorized by the Constitution.

That is why the founders established relatively short terms of office — two years for members of the House of Representatives, four years for president, and six years for senators (with the added safeguard of electing one-third of the senators every two years). They wanted to ensure that the people would have regular, recurring opportunities to decide whether the individuals they selected to exercise government authority were doing what they wanted and, if not, to replace those individuals with others.

So, when the Russian government attempts to influence the outcome of a U.S. election by spreading false and distorted information in favor of one candidate or political party and hacking into election systems, that changes the careful balance struck by the founders. It means that voters, at least some of them, may no longer be making important decisions about governance based solely on their view of what’s in the best interests of the U.S., but on what’s in the best interests of Russia.

The Mueller investigation has to answer many questions, but chief among them are: What actions did the Russian government take to interfere in the 2016 election, and what, if any, impact did those actions have? In the process of finding answers the special counsel is also investigating whether any Americans — including people in the Trump campaign — were working with the Russians and whether any laws were broken.

Mr. Putin’s government has succeeded in interfering in the election of 2016. We’re having another election in nine months. CIA Director Mike Pompeo recently said that he has “every expectation that [the Russian government] will continue to try” to inject themselves into our election process. In other words, they’re coming back.

We need to know what we’re up against and how to combat it. That’s what the Mueller investigation is all about — and why it must continue unobstructed.

Syl Sobel (www.sylsobel.com) is a journalist, a lawyer and the author of children’s books on U.S. history and government, including “How the U.S. Government Works,” “The U.S. Constitution and You” and “Presidential Elections and Other Cool Facts.”