President Trump attacked Democratic rival Joe Biden during the first presidential debate Tuesday night by going after his son Hunter Biden's work in Ukraine, leaning into an issue that led to Trump's impeachment in an attempt to get under the former vice president's skin.

In a pair of combative exchanges on a night full of them, Trump lambasted Biden by raising Hunter Biden's work for Ukrainian gas company Burisma Holdings. Trump first raised the issue during a segment focused on the state of the economy, seizing on allegations that have largely been discredited.

The president accused Hunter Biden of profiting in China while his father was vice president during the Obama administration.

"China ate your lunch, Joe. And no wonder, your son goes there he takes out billions of dollars. Takes out billions of dollars to manage. He makes millions of dollars," Trump said.

He went on to allege the former vice president's son made millions of dollars working for Burisma Holdings and received payments from the former mayor of Moscow. Both have been raised by Republicans in an attempt to question whether there was a conflict of interest while Biden was vice president, but there is no evidence of wrongdoing.

Biden initially avoided engaging, repeating that the allegations were "simply not true."

"None of that is true. It’s totally discredited," Biden said, adding that his son "did nothing wrong at Burisma."

Trump attempted to hold Biden's feet to the fire on the issue, to the point that moderator Chris Wallace had to repeatedly and forcefully ask the president to stop interrupting.

"He doesn’t want to let me answer because he knows I have the truth," Biden said. "His position has been totally thoroughly discredited."

"We want to talk about families and ethics. I don’t want to do that. His family we could talk about all night," Biden added before turning to the camera and saying the debate should be "about your family, the American people."

But the subject of the Biden family came up again later in the debate during a discussion on the military. Biden invoked his late son, Beau Biden, and the president's reported comments that fallen service members were "suckers."

"Are you talking about Hunter?" Trump asked.

"I'm talking about my son, Beau Biden," Biden responded.

"I don't know Beau. I know Hunter," Trump said, alleging that the latter was dishonorably discharged for cocaine use.

Biden acknowledged that his son Hunter had a drug problem, but said he was proud of him for working to overcome it.

The Trump campaign had telegraphed that the president would attack Biden over his son's business dealings. But the strategy carried risks for the president, as his attacks on Hunter Biden and calls for an investigation into the former vice president sparked his impeachment last year.

Hunter Biden joined the board of Burisma Holdings, a natural gas giant in Ukraine, in 2014. The company's founder was under investigation by then-prosecutor general Viktor Shokin, who the U.S., United Kingdom and other Western governments argued had failed to rein in corruption in the country.

The U.S. threatened to withhold roughly $1 billion in loan guarantees if Shokin was not replaced as prosecutor general, a message Joe Biden delivered to officials in Kiev while serving as vice president and recounted during a 2018 Council on Foreign Relations conference.

While many of the president's allies have argued that there was minimally a conflict of interest at play in the case, the former vice president has denied acting with his son's interests in mind and there is no evidence of any criminal wrongdoing by either of the Bidens.

Trump has also claimed that Hunter Biden got $1.5 billion from China, similarly alleging it is evidence of corruption involving the former vice president and his family.

Hunter Biden has business connections to China, but there is no evidence of how much he's made or that it had any relation to his father's work while in office.

Trump was impeached last year by the Democratic-led House on charges of abuse of power and obstruction of Congress. The crux of the investigation focused on the president withholding Ukrainian military aid after asking the country to investigate the Bidens.

The GOP-led Senate later voted to acquit Trump.