Trump froze aid before call with Ukraine's president asking him to probe Biden Trump denies he tied the aid to Ukraine agreeing to investigate Biden.

President Donald Trump ordered that aid to Ukraine be frozen ahead of his call with that country's president, a senior administration official confirmed to ABC News on Tuesday, while Trump acknowledged he raised the question of investigating Vice President Joe Biden and his son, Hunter.

Later Tuesday, speaking at the United Nations after news reports about the action surfaced, President Trump explicitly confirmed he had ordered aid to Ukraine frozen.

"I said hold it up," Trump told reporters during a photo-op with the U.K Prime Minister Boris Johnson. "Let's get others to pay."

"I made that loud and clear," he said and "told it to a lot of people."

His argument that European nations needed to contribute more to Ukraine was a new reason given for his claim he was concerned about sending aid -- beyond the "corruption" in Ukraine that he’s previously cited.

The Washington Post was first to report that Trump ordered Acting Chief of Staff Mick Mulvaney to hold back almost $400 million in military aid at least a week before the July 25 phone call.

Officials at the State Department and the Pentagon were told the president had “concerns” about corruption in Ukraine and wanted to analyze whether the money needed to be spent, the Post cited officials as saying and ABC News confirmed.

Trump on Monday denied that he tied releasing the aid to any investigation, insisting that he put no pressure on the Ukrainian President Volodymyr Zelensky to investigate Joe Biden and his family – but added it “probably possibly” would have been okay had he done so.

“No, no, I didn't,” Trump said when asked if he told the president of Ukraine that they would only get military aid if they investigated Biden during a pool spray of his meeting with Poland's president.

“I put no pressure on them, whatsoever,” Trump said of his call. “I could have, I think it would have probably possibly have been okay if I did, but I didn't I didn't put any pressure on them whatsoever, you know why because they want to do the right thing and they know about corruption, and they probably know that Joe Biden and his son are corrupt, they probably know that Joe Biden and his son are corrupt. Joe Biden and his son are corrupt.

Arriving at the United Nations Tuesday morning, he again defended his actions.

“That call was perfect. It couldn't have been nicer. Even the Ukrainian government put out a statement that that was a perfect call There was no pressure put on them whatsoever. But there was pressure put on with respect to Joe Biden. What Joe Biden did for his son, that's something they should be looking at,” Trump said.

"When you see the readout of the call, which I assume you’ll see at some point," he told reporters, they would understand the controversy was "nonsense." Trump and the White House officials were considering whether to release a transcript of the call, which Trump has both said he would like to do but then said conversations between himself and world leaders should be kept private.

The president elaborated on his assertion that the U.S. is paying more than its fair share compared to European allies.

“As far as withholding funds, those funds were paid. They were fully paid. But my complaint has always been and I withhold again and I'll continue to withhold until such time as Europe and other nations contribute to Ukraine,” Trump said.

He continued: “What I want and I insist on it is Europe has to put up money for Ukraine also. Why is it only the United States putting up the money? And by the way, we paid that money. But I always ask, aren't other countries in Europe especially putting up money for Ukraine?”

Trump's comments Tuesday came as House Democrats, responding to the Ukraine call controversy, were set to meet Tuesday afternoon about possibly moving ahead with impeachment proceedings.

Asked about House Speaker Nancy Pelosi and the growing calls for impeachment over the controversy over his Ukraine call, the president dismissed it as "nonsense."

“I think it's ridiculous. It's a witch hunt. I'm leading in the polls. They have no idea how they stop me. The only way they can try is through impeachment. This has never happened to a president before. There's never been a thing like this before. It's nonsense,” Trump said.