McMaster is a retired U.S. Army lieutenant general, who served as the 25 th United States National Security Advisor from 2017 to 2018, under Trump. He is currently a senior fellow at the Hoover Institution at Stanford University. Newsweek reached out to McMaster via email for further comment.

"I would appeal to his sense of, 'Don't be a loser,'" Rep. McCaul says he'd tell Trump regarding aid to Ukraine. "You don't want to lose this."

Trump has promised to end Russia's full-scale invasion of Ukraine within a day if elected but has not publicly elaborated on how he plans to achieve that.

The new head of NATO is vowing to help shore up Western support for war-ravaged Ukraine and says he can work with whoever is elected president of the United States, the alliance’s most powerful member.

NATO's new chief Mark Rutte voiced strong support for Ukraine on Tuesday and said he was not worried about the upcoming U.S. election as he could work with former President Donald Trump or Vice President Kamala Harris.

Ukraine said it struck a stockpile of weapons in Russia overnight that may have included just-arrived missiles from Iran.

Ukraine on Sunday said it sent more than 100 drones deep inside Russia to hit a major weapons depot, as it stepped up attacks further inside Russian territory.