US President-elect Donald Trump reiterated his campaign promises to impose trade tariffs and carry out mass deportations on Sunday, while also hinting at the possibility of withdrawing from NATO.

In his first major televised interview, six weeks before taking office, Trump said he would "absolutely" consider leaving NATO if allies didn't "pay their bills."

"They have to pay their bills," Trump told NBC's "Meet the Press," saying he would "absolutely" consider taking the United States out of the alliance unless members are "treating us fairly."

He also suggested that US backing for Ukraine would be reduced, stating he would "probably" limit funds to Kiev, which the United States has been steadfastly backing since the war in Ukraine broke out.

"Possibly. Yeah, probably, sure," he told the US news outlet.