Following the latest explosive details about Donald Trump Jr.'s meeting with a Kremlin-connected lawyer during last year's campaign, in which he hoped to receive damaging information about Hillary Clinton, legal experts are saying the encounter could be proof that "collusion"—or even "treason"—took place.

Trump Jr. confirmed the New York Times' initial reports that he attended the meeting with Natalia Veselnitskaya (infamous for challenging the Magnitsky Act, which blacklists suspected Russian human rights abusers) at Trump Tower, along with then-campaign chairman Paul J. Manafort, and Jared Kushner, the president’s son-in-law.

However, Trump Jr. and Manafort have since lawyered up, with the Times reporting Monday that Jr. "was informed in an email" that Veselnitskaya's promised dirt on Clinton "was part of a Russian government effort to aid his father’s candidacy."

In the wake of the Monday's report, the government ethics watchdogs at CREW said it would be "hard to overstate how huge this is."

MSNBC's chief legal correspondent, Ari Melber, laid out the legal implications on Twitter:

Legally significant because this is
(1) written evidence
(2) before the meeting
(3) stating Russian gov involvement https://t.co/Ae5QbK0sh4

— Ari Melber (@AriMelber) July 11, 2017

Washington Post columnist Eugene Robinson called the latest revelations a "legal game-changer" because it shows top members of the Trump campaign—in this case the president's own son—willing to accept information believed to be coming from a foreign government.

"Despite what Trump apologists may say, it is not normal practice for a campaign to welcome information undermining an opponent, regardless of the source," explained Robinson. "In 2000, the Al Gore campaign was anonymously sent briefing books and a video that George W. Bush had used to prepare for an upcoming debate. Gore campaign officials immediately turned the material over to the FBI—which opened a criminal investigation."

Trump Jr.'s lawyer claims the reports are "much ado about nothing," but former assistant Watergate special prosecutor Jill Wine-Banks disagrees.

"It is collusion with a foreign adversary if they were working together to get the information from the Russian government," she said Monday night on MSNBC. "And that's what this looks like, it looks like clear proof of collusion."

But even before Monday's revelations, there was talk of treason among legal experts.

"This was an effort to get opposition research on an opponent in an American political campaign from the Russians, who were known to be engaged in spying inside the United States," said Richard Painter, an ethics lawyer under former President George W. Bush, on Sunday. "We do not get our opposition research from spies, we do not collaborate with Russian spies, unless we want to be accused of treason."

"This is unacceptable," he added. "This borders on treason, if it is not itself treason."