-- Donald Trump Jr. has come back swinging after news broke on Sunday that he, along with Donald Trump Sr.'s son-in-law, Jared Kushner, and then–campaign chairman, Paul Manafort, met with Russian lawyer Natalia Veselnitskaya before the presidential election last year.
On Monday, Donald Trump Jr. tweeted, "Obviously I'm the first person on a campaign to ever take a meeting to hear info about an opponent... went nowhere but had to listen."
Trump said on Sunday in a statement received by ABC News, "I was asked to have a meeting by an acquaintance I knew from the 2013 Miss Universe pageant with an individual who I was told might have information helpful to the campaign."
"I was not told her name prior to the meeting. I asked Jared and Paul to attend but told them nothing of the substance," the statement read.
"We had a meeting in June 2016. After pleasantries were exchanged, the woman stated that she had information that individuals connected to Russia were funding the Democratic National Committee and supporting [Hillary] Clinton."
"[Veselnitskaya's] statements were vague, ambiguous and made no sense. No details or supporting information was provided or even offered. It quickly became clear that she had no meaningful information," he said.
Trump added that his father knew nothing of the meeting, and the president's personal legal team said Donald Trump Sr. did not attend the meeting and had not been aware of it.
Meeting warrants investigation, said experts
Legal experts told ABC News that, based on news reports, it warrants investigation into whether Donald Trump Jr., Kushner and Manafort violated any laws.
"This new information provides grist for the mill under the federal election laws," said Kenneth Gross, a campaign law attorney with Skadden, Arps, Slate, Meagher & Flom LLP.
Federal laws prohibit anyone from soliciting or accepting any campaign contribution from a foreign national or foreign government.
"No person shall knowingly solicit, accept or receive from a foreign national any contribution or donation," reads Title 11 in the Code of Federal Regulations, section 110.20 (g). A contribution can be "anything of value," including negative information about a political opponent.
It is unlawful to "provide substantial assistance in the solicitation, making, acceptance or receipt of a contribution or donation," reads 11 CFR 110.20 (h).
Experts said it can be difficult to determine whether unlawful solicitation has occurred, as there is little established law or precedent in this area.
Simply attending the meeting with Veselnitskaya almost certainly did not cross that line, said experts.
There are "no magic words" to turn this into solicitation, said Kathleen Clark, a law professor at Washington University School of Law. "You have to look at the context. Was Don Jr. attempting to induce someone?"
To make this unlawful, Trump, Kushner and Manafort would have to "ask for something, and it would have to be an express or implied ask," said Rick Hasen, an election law expert at the University of California at Irvine. And they would have to know whom they were meeting, he added.
If Veselnitskaya had no information on Clinton, as Trump has claimed, that should not matter for purposes of solicitation.
"If I offer a judge $1 million to decide a case my way, that's a crime, even if judge says no and no money changes hands. Solicitation is enough," Hasen pointed out in a tweet.
"Solicitation need not be successful in order to be illegal," Bob Bauer, a White House counsel under Barack Obama, wrote in a blog post.
Accepting a contribution
If Trump, Kushner and Manafort accepted information on Clinton from Veselnitskaya, then a legal case against them would be fairly clear cut, said legal experts.
Prosecutors would need to show that a foreign national or foreign government spent some money to obtain the research or information on Clinton and that the three knowingly accepted it.
Could this be prosecuted?
If there was a violation of these laws, the Federal Election Commission could bring a civil action against Trump, Kushner or Manafort. The FEC has the power to impose a fine or bring an administrative action.
Violations of campaign finance laws can, in dramatic cases, constitute a crime, even a felony. Prosecutors with the Department of Justice would have a very high bar of proving criminal intent and knowing and willful action.
How else could this be unlawful?
Trump, Kushner and Manafort could also face legal exposure if there is evidence that they lied under oath, gave the government false information or failed to report certain campaign activities, said experts.
"The slogan 'the cover-up is worse than the crime' could certainly apply here," said Clark.
Additionally, experts said, the meeting could be wrapped into other pending or future investigations of Russian election meddling, obstruction of justice, collusion or conspiracy.