© Reuters/Carlos Barria
US President Donald Trump • Former National Security Advisor John Bolton
President Trump rejected a reported claim by former National Security Adviser John Bolton early Monday that he tied military aid to Ukraine to investigations of Democratic candidate Joseph Biden.

"I NEVER told John Bolton that the aid to Ukraine was tied to investigations into Democrats, including the Bidens," the president tweeted after midnight. "In fact, he never complained about this at the time of his very public termination. If John Bolton said this, it was only to sell a book."

The New York Times reported the conversation in a draft of a forthcoming book by Mr. Bolton, prompting Democrats to renew calls for his testimony in the president's impeachment trial.

Mr. Trump said transcripts of his calls with Ukraine's president "are all the proof that is needed." "Additionally, I met with President [Volodymry] Zelensky at the United Nations ... ... (Democrats said I never met) and released the military aid to Ukraine without any conditions or investigations - and far ahead of schedule," he tweeted. " I also allowed Ukraine to purchase Javelin anti-tank missiles. My Administration has done far more than the previous Administration."

The president also said on Monday that the Senate shouldn't be able to call Mr. Bolton as a witness in the trial.

"The Democrat controlled House never even asked John Bolton to testify," the president tweeted. "It is up to them, not up to the Senate!"