He says nobody’s tougher on America’s enemies than him; White flags and love letters.

One of the witnesses in Donald Trump's first impeachment shamed the former president's lack of knowledge about World War II.

The ex-president and current Republican nominee mocked president Joe Biden for backing Ukraine, saying the embattled nation didn't stand a chance against Russia because the invaders were too militarily powerful.

"Biden says, ‘We will not leave until we win,’” Trump said Tuesday at a rally in Savannah, Georgia. “What happens if they win? That’s what they do, is they fight wars. As somebody told me the other day, they beat Hitler, they beat Napoleon. That’s what they do. They fight, and it’s not pleasant.”

Retired lieutenant colonel Alexander Vindman, a former high-ranking official with the National Security Council who testified as part of the Trump-Ukraine scandal, expressed shock at the former commander in chief's dim understanding of military history.

"First, I have to address this commentary," Vindman told CNN. "I mean, just the other day somebody told him about World War II? I mean, how preposterous is this? It is embarrassing that a former president would say, even use that kind of language, that he just learned about World War II and his false impressions of how the records of the Soviet Union performed, really at the backbone was support from the West in massive casualties that they took. But I think I would say that we would be facing a different kind of disaster. It wouldn't be a complete collapse of the Ukrainians."

"The fact is that the Europeans are spending more money on Ukraine," Vindman added. "They're putting more resources in Ukraine, but they don't have that defense industrial base to a really provide the adequate support for Ukraine to gain ground. So we will probably see it's a shift to the Russians being more effective in their offensive operations, slowly grinding down the Ukrainian military and making incremental gains. But that would result in the Europeans recognizing that there's no longer U.S. support doubling down and providing more aid, including troops. Why? Because they have to send a message to Russia that a Russian attack, more Russian aggression against Europe will not be tolerated, and the only way they could do that is by ramping up. They couldn't be weak-kneed at that point because they know that Europe would be the next target."