WASHINGTON — The Mueller report has landed. Here's what that means.

The special counsel's 22-month investigation into possible coordination between the Trump campaign and Russia … is over.

According to the rules, Robert Mueller had to submit a confidential report to the attorney general "at the conclusion of the special counsel's work."

A senior law enforcement official told NBC News that once the report has been submitted, it means Mueller has finished his investigation.

That doesn't necessarily spell the end of criminal jeopardy for some of the people around President Donald Trump who have not been charged. It's been well-documented that Mueller farmed out investigative leads to other parts of the Justice Department, and that New York prosecutors are investigating individuals in the Trump Organization.

But the report's transmission does indicate that Mueller decided not to charge any member of the Trump campaign with conspiracy — or "collusion" — with the Russian election interference effort. After it was transmitted, a senior Justice Department official confirmed to NBC News that the special counsel is not recommending any additional indictments. And there are no sealed Mueller indictments.

That's a big deal.

Trump will likely claim victory, arguing that his "no collusion" mantra was right all along.

Download the NBC News mobile app for breaking news alerts and full coverage of the Mueller report.

But whether Trump can fairly claim a measure of vindication will depend a lot on what Mueller's report says about his conduct, something we don't yet know. In a Friday afternoon letter to the leaders of the Senate and House Judiciary committees notifying them he had received the report, Attorney General William Barr said, "I am reviewing the report and anticipate that I may be in a position to advise you of the Special Counsel's principal conclusions as soon as this weekend."

The unknowns are huge:

How detailed will Mueller's confidential report be? The rules say he has to explain his decisions not to prosecute, but they don't place any limits on content or detail.

What, if anything, will the report say about whether the president tried to obstruct justice, a question Mueller examined in depth?

Will the report disclose previously unknown interactions between Trump associates and Russians?

Will it make any assessment about the president's motives and judgments regarding his praise of Russian President Vladimir Putin and WikiLeaks, the entity that received and published Democratic emails hacked by Russian intelligence officers?

What were the results of the FBI's counterintelligence investigation into whether the president was under the sway — or compromised in any way — by Putin?

Another complication: To the extent that Mueller has answered these questions, some of the answers may be based on classified intelligence. Others will be based on grand jury testimony that is subject to secrecy rules. Barr will have to decide how to handle that.

But whatever he decides, Congressional Democrats will not be satisfied.

They have already said they will push for the release of the full Mueller report, and subpoena it, if necessary.

House Intelligence Committee Chairman Adam Schiff has also made clear the FBI has a separate legal obligation to report to the intelligence committees its findings about counterintelligence issues regarding the president and those around him. In other words, any evidence that Trump or his associates were or are in thrall to Russia, a notion the White House calls ridiculous.

Meanwhile, other investigations continue.

Federal prosecutors in New York are continuing to investigate the Trump inaugural committee and individuals in the Trump Organization.

Former National Security Adviser Mike Flynn has provided information relevant to an undisclosed, separate federal investigation, according to court records.

A law enforcement official with direct knowledge told NBC News that both counterintelligence and political corruption cases have been spun off by Mueller's office.

The Washington Post reported that the Justice Department's public integrity section is investigating whether a Trump fundraiser tried to sell access to foreign governments.

The Senate Intelligence Committee is conducting a bipartisan investigation that will result in a number of public reports about what happened in the 2016 election.

And House Democrats are pursuing the broader question of possible Trump financial ties to Russia — a question they are not sure Mueller fully investigated.

This much is clear: The story of Trump, Russia and the 2016 election has not yet been fully told. And the investigations that bedevil his presidency are not over.

But for now, at least one legal cloud over Trump has dissipated. The special counsel has apparently finished his work without charging a criminal conspiracy between Trump's campaign and a foreign intelligence effort to help him win.