Joe Biden claimed on Friday he was unaware his youngest son, Hunter, was serving on the board of directors of a Ukrainian oil and gas giant while Biden was responsible for Obama administration policy towards the country.

The former vice president made the claim during an interview with PBS News Hour in which he was asked why a recent campaign pledge to not have children “involved” with foreign countries did not apply to his eight year tenure in the Obama White House. Biden responded to the question by asserting “no one” had established either he or his son has done “anything wrong” in their professional and business dealings in Ukraine, before alleging he had no knowledge of his son’s position with Burisma Holdings.

“I did not know he was on the board of that company,” the former vice president said. “In fact, no one has asserted on the board that it was illegal for him to be on the board or that he did anything wrong.”

When asked if he would have interceded with his son had “he known” about the appointment, Biden again reiterated his son did “nothing wrong”

The former vice president’s claim to not have known about his son’s position with Burisma, however, has been undercut by numerous sources, including Hunter Biden himself. The younger Biden admitted during a series of candid interviews for a New Yorker profile published in June that he in fact had discussed his foreign business interests with his father on at least one occasion.

“Dad said, ‘I hope you know what you are doing,’ and I said, ‘I do’” Hunter Biden told the magazine.

The contradicting stories between father and son only underscore the multiple unanswered questions surrounding Hunter Biden’s work in Ukraine. At the center of controversy is how and why Hunter Biden secured an appointment to Burisma’s board of directors, which at times paid more than $83,000 a month.

As Peter Schweizer, senior contributor at Breitbart News, detailed in his book, Secret Empires: How the American Political Class Hides Corruption and Enriches Family and Friends, Hunter Biden had no prior experience with either the energy industry or Ukraine before joining Burisma in April 2014. In fact, his background in investment banking, lobbying, and hedge fund management paled in comparison to that of current and past members of the company’s board of directors.

At the time of his appointment, ethics watchdogs highlighted the younger Biden’s lack of qualifications but were more concerned about the appearance of a conflict of interest. In particular, many worried Hunter Biden’s ascension to the board of directors, a position that paid at times more than $83,000 per month, was related to his father’s position as the Obama administration’s point man on Ukraine.

The poor optics not only raised flags among ethics watchdogs but also with Hunter Biden’s own business partners. Christopher Heinz, the stepson of former Secretary of State John Kerry and co-owner of an investment firm with Hunter Biden in 2014, rushed to play damage control with State Department officials at the time of the appointment, according to internal emails obtained by the Washington Examiner. 

Adding to concerns is the fact that at the time Hunter Biden joined Burisma, the company was seen as actively courting western leaders to prevent further scrutiny of its business practices. The same month Hunter Biden was tapped for the group’s board, the government of Great Britain froze accounts belonging to Burisma founder Mykola Zlochevsky under suspicion of money laundering.

Zlochevsky, a former Ukrainian minister of natural resources, would later be accused of corruption for using his office to approve oil and gas licenses to companies under his control. A Ukrainian official with strong ties to Zlochevsky admitted in October the only reason that Hunter Biden secured the appointment was to “protect” the company from foreign scrutiny.

Joe Biden’s role in the entire matter has only increased suspicions of conflicting interests. As the sitting vice president, Joe Biden led the Obama administration’s response to the Russian invasion of Crimea in 2014. In that role, he pushed billions of dollars in aid to the Ukrainian government, some of which allegedly was filtered to Burisma.

More troubling, however, is an episode that took place in 2016, when Joe Biden pressured the Ukrainian government to fire Viktor Shokin, the country’s top prosecutor.

Officially, the former vice president has claimed his threat to withhold U.S. aid to Ukraine if Shokin was not fired came from the Obama administration, which had lost confidence in the prosecutor’s abilities to root out corruption.

Unofficially, though, it was well known that Shokin was investigating both Burisma and Zlochevsky for wrongdoing. Regardless of the reason, Shokin’s successor closed the investigation into Burisma and Zlochevsky, allowing the oligarch to return to the country after having fled it in 2014.

The appearance of impropriety has only been underscored by comments Hunter Biden made in a recent ABC News interview, where he admitted his father’s political influence was likely the reason for his appointment to Burisma’s board.

“I don’t know. I don’t know. Probably not, in retrospect,” the younger Biden said when asked if he would have been tapped for the lucrative job had his father not been the sitting vice president. He quickly added, though, that his family’s political prominence had always played a large role in his dealings. “But that’s—you know—I don’t think that there’s a lot of things that would have happened in my life if my last name wasn’t Biden.”