New York, New York - Donald Trump doubled down Sunday on his extreme campaign pledges to impose trade tariffs and carry out mass deportations, while dangling the idea that the US could withdraw from NATO.

In his first sit-down TV interview – and just six weeks before he takes office – Trump again signaled that US support for Ukraine will scale back, saying he will "probably" cut the aid helping Kyiv repel the Russian invasion.

Trump also said he would "very quickly" look at pardons for supporters jailed for storming the Capitol after his 2020 election defeat to Joe Biden.

The interview with NBC's Meet the Press host Kristen Welker was taped Friday but aired Sunday, following Trump's meetings with the presidents of France and Ukraine over the weekend – his first foreign trip since winning the November election against Biden.

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Trump reiterated his familiar threat to leave NATO, saying that US allies do not pay enough for their defense.

"If they're paying their bills, and if I think they're treating us fairly, the answer is absolutely I'd stay with NATO," said.

But there is also "absolutely" the possibility of America's departure, he said.

He also stressed that his campaign promises of huge tariffs – including against top US trading partners Canada, Mexico, and China – would be enacted.

"We're subsidizing Mexico, and we're subsidizing Canada, and we're subsidizing many countries all over the world," he said.

Vowing that "properly used" tariffs are "a very powerful tool," Trump added that he would not only wield them economically, "but also for getting other things outside of economics."

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When asked whether Americans would see higher prices as a result of those tariffs, Trump only said that he "can't guarantee anything."

He also promised he would go ahead with the unprecedented deportation of immigrants, while also launching an attack on the constitutionally protected right to US citizenship for anyone born in the country.

"I think you have to do it, and it's a hard – it's a very tough thing to do. But you have to have rules, regulations, laws. They came in illegally," Trump said.

"We're going to have to get it changed. We'll maybe have to go back to the people. But we have to end it," he added, referring to the 14th Amendment.