Vice President Kamala Harris appeared Friday to reference former President Trump's recent anti-NATO comments, warning that "history offers a clue" as to what happens when an aggressor goes unchecked.

Why it matters: Harris used her speech to the annual Munich Security Conference to contrast President Biden's foreign policy and that of his likely 2024 opponent.

• While she didn't refer to Trump by name, Harris lamented that "some" in the U.S. have questioned its commitment to the military alliance's collective defense principle.
• Trump during a campaign rally in South Carolina last weekend said he told the president of an unidentified NATO member that he would "encourage" Russia "to do whatever the hell they want" if that country was not hitting NATO's target of spending 2% of GDP on defense.

Driving the news: Harris emphasized Friday how NATO has grown stronger during Biden's presidency, with far more countries now hitting the 2% target and Finland having joined, with Sweden expected to follow.

• Harris, who had a friendly audience at the annual gathering of the Western foreign policy establishment in Munich, warned: "None of the gains we have made will be permanent unless we are vigilant."
• "Imagine if America turned our back on Ukraine and abandoned our NATO allies and abandoned our treaty commitments," Harris continued. "Imagine if we went easy on [Russian President Vladimir] Putin, let alone encouraged him."
• "History offers a clue. If we stand by while an aggressor invades its neighbor with impunity, they will keep going. And in the case of Putin, that means all of Europe would be threatened."

Between the lines: A growing proportion of the U.S. public backs Trump's arguments that the U.S. should stop spending billions to defend Ukraine.

• His willingness to hang treaty allies out to dry may be less popular, however. The Biden administration has seized on the NATO comments as an indication that Trump's return would endanger global security.
• The president has called the comments "appalling and dangerous," as well as "un-American." NATO Secretary General Jens Stoltenberg warned that Trump's threats put U.S. and European soldiers "at increased risk."

Ahead of her speech, Harris said the U.S. was working to confirm the "terrible news" that Russian opposition leader Alexei Navalny had died.

• "If confirmed, this would be a further sign of Putin's brutality. Whatever story they tell, let us be clear: Russia is responsible," Harris said. She noted that Navalny's wife Yulia was present at the conference in Munich.

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