President Trump tweeted Sunday that the purpose of the 2016 Trump Tower meeting between Russians, Donald Trump Jr., and some of his top campaign officials was "to get information on an opponent."

Why it matters: The claim represents the latest in a series of shifting explanations from the Trump team about the true nature of the June 9, 2016 meeting, which was first described as a "short introductory meeting" about Russian adoptions last summer before culminating with the president's admission this morning.

In his tweet, Trump seemingly referenced an article from The Washington Post headlined, "Trump at a precarious moment in his presidency: Privately brooding and publicly roaring":

"Still, Trump has confided to friends and advisers that he is worried the Mueller probe could destroy the lives of what he calls “innocent and decent people” — namely Trump Jr., who is under scrutiny by Mueller for his role organizing a June 2016 meeting at Trump Tower with Russians promising dirt on Hillary Clinton."

to friends and advisers that he is worried the Mueller probe could destroy the lives of what he calls “innocent and decent people” — namely Trump Jr., who is under scrutiny by Mueller for his role organizing a June 2016 meeting at Trump Tower with Russians promising dirt on Hillary Clinton." "As one adviser described the president’s thinking, he does not believe his son purposefully broke the law, but is fearful nonetheless that Trump Jr. inadvertently may have wandered into legal ­jeopardy."

A timeline of the shifting stories on the meeting:

July 24, 2016: Donald Trump Jr. appears on CNN and dismisses the notion that the hacking of the DNC's emails was part of a Russian plot to help his father in the election: "Well, it just goes to show you their exact moral compass. I mean, they will say anything to be able to win this. I mean, this is time and time again, lie after lie."

Donald Trump Jr. appears on CNN and dismisses the notion that the hacking of the DNC's emails was part of a Russian plot to help his father in the election: "Well, it just goes to show you their exact moral compass. I mean, they will say anything to be able to win this. I mean, this is time and time again, lie after lie." July 8, 2017: The New York Times breaks the news about the meeting. Trump Jr. issues a statement saying it was a "short introductory meeting" that was primarily about Russian adoptions.

The New York Times breaks the news about the meeting. Trump Jr. issues a statement saying it was a "short introductory meeting" that was primarily about Russian adoptions. July 9, 2017: The Times publishes a second story reporting that Trump Jr. was promised damaging information about Hillary Clinton in advance of the meeting. He issues a second statement saying the Russian lawyer offered "vague, ambiguous" claims of dirt on Clinton, but that nothing meaningful came from the meeting.

The Times publishes a second story reporting that Trump Jr. was promised damaging information about Hillary Clinton in advance of the meeting. He issues a second statement saying the Russian lawyer offered "vague, ambiguous" claims of dirt on Clinton, but that nothing meaningful came from the meeting. July 11, 2017: To get ahead of a Times article that would be published minutes later, Trump Jr. tweets screenshots of the email exchange in which the meeting was organized. The emails indicate an interest in obtaining incriminating information and a tacit acknowledgement by Trump Jr. of the Russian government's support for his father.

To get ahead of a Times article that would be published minutes later, Trump Jr. tweets screenshots of the email exchange in which the meeting was organized. The emails indicate an interest in obtaining incriminating information and a tacit acknowledgement by Trump Jr. of the Russian government's support for his father. July 12-16, 2017: President Trump's lawyer Jay Sekulow appears on several cable news shows and denies that the president had any involvement in drafting his son's initial statement to the Times.

President Trump's lawyer Jay Sekulow appears on several cable news shows and denies that the president had any involvement in drafting his son's initial statement to the Times. June 2, 2018: The Times publishes a letter from Trump's lawyers to Robert Mueller conceding that the president dictated "a short but accurate" statement issued by his son about the meeting.

The Times publishes a letter from Trump's lawyers to Robert Mueller conceding that the president dictated "a short but accurate" statement issued by his son about the meeting. July 26, 2018: Former Trump attorney Michael Cohen claims the president approved "going ahead" with the meeting, contradicting denials of any prior knowledge by Trump's legal team.

Former Trump attorney Michael Cohen claims the president approved "going ahead" with the meeting, contradicting denials of any prior knowledge by Trump's legal team. Aug. 5, 2018: Trump again denies having any advanced knowledge, but claims that it was a "totally legal" meeting to "get information on an opponent" — something that is "done all the time in politics"

What they're saying: