Eric Trump responded to MSNBC host Lawrence O’Donnell’s decision to quote an unsourced claim that Russian oligarchs cosigned Donald Trump’s loans, signaling that the Trump Organization will take legal action despite O’Donnell’s apology.

O’Donnell apologized in both a tweet and on his show Wednesday evening after citing a “single source close to Deutsche Bank” who claimed that “Russian billionaires close to Vladimir Putin” cosigned Trump’s loans.

However, Eric Trump, executive vice president of the Trump Organization, signaled that the company will take legal action as a response to O’Donnell’s charge.

“This was a reckless attempt to slander our family and smear a great company,” Trump wrote.

“Apologies are not enough when the true intent was solely to damage and cause harm,” he continued. “As a company, we will be taking legal action. This unethical behavior has to stop”:

This was a reckless attempt to slander our family and smear a great company. Apologies are not enough when the true intent was solely to damage and cause harm. As a company, we will be taking legal action. This unethical behavior has to stop. @Lawrence @MSNBC https://t.co/i4X6CcdkCm — Eric Trump (@EricTrump) August 29, 2019

The tangle started on Tuesday after O’Donnell cited a “single source close to Deutsche Bank” who reportedly told O’Donnell that Russian oligarchs cosigned Trump’s loan documents.

“That’s how he was able to obtain those loans. … The cosigners are Russian oligarchs,” O’Donnell said.

“If true, that would be a significant factor in Vladimir Putin’s publicly stated preference for presidential candidate Donald Trump over presidential candidate Hillary Clinton,” he continued.

Trump, through his lawyers, demanded a retraction, calling the claims “false and defamatory.”

“These statements are false and defamatory, and extremely damaging,” the president’s lawyer, Charles Harder of Harder LLP law firm, wrote. “The only borrowers under these loans are Trump entities, and Mr. Trump is the only guarantor.”

“Demand is hereby made that Mr. O’Donnell and NBCU immediately and prominently retract, correct and apologize for the aforementioned false and defamatory statements,” Harder added.

“Last night I made an error in judgment by reporting an item about the president’s finances that didn’t go through our rigorous verification and standards process. I shouldn’t have reported it and I was wrong to discuss it on the air,” O’Donnell tweeted in part Thursday:

Last night I made an error in judgment by reporting an item about the president’s finances that didn’t go through our rigorous verification and standards process. I shouldn’t have reported it and I was wrong to discuss it on the air. I will address the issue on my show tonight. — Lawrence O'Donnell (@Lawrence) August 28, 2019

As promised, O’Donnell addressed the controversy on his show.

“Last night, on this show, I discussed information that wasn’t ready for reporting. I repeated statements a single source told me about the president’s finances and loan documents with Deutsche Bank,” he said.

“Saying ‘if true’ as I discussed the information was simply not good enough,” he continued:

I did not go through the rigorous verification and standards process here at MSNBC before repeating what I heard from my source. Had it gone through that process, I would not have been permitted to report it. I should not have said it on air or posted it on Twitter. I was wrong to do so. This afternoon, attorneys for the president sent us a letter asserting the story is false. They also demanded a retraction. Tonight, we are retracting the story. We don’t know whether the information is inaccurate. But, the fact is, we do know it wasn’t ready for broadcast, and for that, I apologize.”

WATCH: Lawrence O'Donnell retracts his reporting about Trump loans. pic.twitter.com/JxNsIPhBNg — MSNBC (@MSNBC) August 29, 2019

However, his original, problematic tweet remained up as of Thursday morning:

A source close to Deutsche Bank says Trump’s tax returns show he pays very little income tax and, more importantly, that his loans have Russian co-signers. If true, that explains every kind word Trump has ever said about Russia and Putin. @TheLastWord 10pm — Lawrence O'Donnell (@Lawrence) August 28, 2019

Trump responded to O’Donnell’s apology in a tweet Thursday morning:

….for the most ridiculous claim of all, that Russia, Russia, Russia, or Russian oligarchs, co-signed loan documents for me, a guarantee. Totally false, as is virtually everything else he, and much of the rest of the LameStream Media, has said about me for years. ALL APOLOGIZE! — Donald J. Trump (@realDonaldTrump) August 29, 2019