Special counsel Robert S. Mueller III has delivered his report to the attorney general. We don’t know the details of the report or what Mueller has concluded. And there are many other unknowns concerning apparent loose ends from Mueller’s inquiry and the outcome of other pending investigations.

But one thing seems clear, and it’s huge: Mueller will not be charging a criminal conspiracy involving members of the Trump campaign and the Russians who sought to interfere with the 2016 presidential election.

There were three main areas of Mueller’s investigation: 1) the Russian efforts to interfere with the election; 2) any involvement by members of the Trump campaign in that interference; and 3) crimes arising out of the investigation itself, such as perjury and obstruction of justice.

In the first area, Mueller brought two indictments against more than two dozen Russians for seeking to influence the election through fake social media campaigns and by stealing and releasing Democratic emails. Those indictments themselves served as a kind of “Mueller report,” providing great detail concerning the Russian attacks on our election.

In the third area, Trump’s former national security adviser Michael Flynn, former personal attorney Michael Cohen and former campaign adviser George Papadopoulos — to name a few — were convicted of lying to Mueller’s investigators or to Congress about various contacts between the Trump campaign and Russia.

But the remaining great unknown was the second area: Were any Americans working with the Russians seeking to tip the election? The president, his lawyers and many in the media have called this “collusion,” but as I and others have repeatedly pointed out, the proper criminal term is “conspiracy.” The question was whether interactions between the Trump campaign and the Russians rose to the level of a provable criminal conspiracy. It appears Mueller has concluded the answer to that question is no. Even if Mueller felt bound by Justice Department policy not to indict the president himself, if he had found such a conspiracy, nothing would have prevented him from charging the other participants. But that conspiracy indictment is not forthcoming.

To be sure, there were scores of suspicious interactions between Russians and members of the Trump campaign. Some of them may rise to the level of collusion — depending on how one defines that term. But the bar to proving a criminal conspiracy is far higher and requires much more than suspicious meetings or contacts.

That Mueller did not charge a criminal conspiracy does not, of course, excuse or explain the many documented contacts between the Trump campaign and Russia. There are many actions that are deplorable, naive, reckless or unwise that are not criminal. Those contacts may prove to have political consequences for the president, even if they do not have criminal ones. And the counterintelligence aspects of Mueller’s investigation may reveal details that raise grave national security concerns, even if they fall short of being indictable.

It’s also true that the Mueller probe was only one of several ongoing investigations that may put the president or those close to him in criminal jeopardy. For example, the U.S. attorney’s office for the Southern District of New York is investigating possible campaign finance violations and possible financial misconduct involving the president’s inaugural committee, and likely other allegations involving the president and his business dealings. The ongoing investigations in that office could ultimately pose a greater threat to Trump than Mueller ever did.

We also don’t know how many other investigations Mueller may have “spun off” to other prosecutor’s offices because they fell outside his mandate. For example, House lawmakers reportedly sent Mueller dozens of witness transcripts to examine for possible perjury or false-statements charges, akin to those filed against Cohen and longtime Trump confidant Roger Stone. Are those cases already resolved, or has Mueller referred them for investigation to the U.S. attorney for the District of Columbia?

Also still unknown is the full impact of the cooperation by Rick Gates, Trump’s former deputy campaign manager. Just last week, his sentencing was continued once again, and prosecutors told the court he continues to cooperate in “several ongoing investigations.” The intriguing word here is “several.” One of those investigations is likely that involving the inaugural committee, where Gates served as the deputy chair. But what are the others?

So it’s safe to say the conclusion of the Mueller probe does not mark the end of the president’s legal woes. Much is still unknown, and much more is still to come, including possible additional indictments from other offices. But Mueller wrapping up without further criminal charges is still a blockbuster development.

Mueller is a pro and ran a thoroughly professional investigation. He didn’t leak and didn’t respond to the president’s repeated attacks but simply kept his head down and did his job. We know, from Attorney General William P. Barr’s letter to Congress on Friday, that Mueller was never overruled by the attorney general and was able to proceed unimpeded. The public can have a great deal of confidence in his conclusions, whatever they are.

And Mueller apparently has concluded there is no basis to charge that the sitting president of the United States and his campaign criminally conspired with a foreign adversary to win the election. Whatever else is coming, this conclusion, at least, should cause the entire country, not just the White House, to breathe a sigh of relief.

Read more:

Patrick Leahy: Mr. President, beware the mistakes of Richard Nixon

The Post’s View: Mueller has submitted his report. Now Barr must share it with the rest of us.

Erik Wemple: The Mueller report: How long can cable news talk about a document it doesn’t have?

Harry Litman: The Mueller report will be released, one way or the other

Neal Katyal: I wrote the special counsel rules. The attorney general can — and should — release the Mueller report.