Liz Cheney says Donald Trump’s recent threats against NATO allies demonstrate a “dangerous” misunderstanding of America’s foreign diplomacy.

In a Sunday interview on CNN’s “State of the Union,” the former congresswoman told Jake Tapper she was outraged by Trump, who earlier this month said he would “encourage” Russian President Vladimir Putin to attack NATO signatories that aren’t spending enough on defense funding.

“It’s dangerous, it shows a complete lack of understanding of America’s role in the world,” Cheney said. “It’s disgraceful.”

While Trump has repeatedly complained about NATO countries being behind on their “bills,” the alliance doesn’t exactly work that way.

NATO is anchored in the principle of mutual defense, meaning each member country must commit to enough defense spending to ensure their nation’s militaries are prepared to step in if another member of the alliance is attacked.

The agreement’s Article 5 says signatories must treat an attack on one as an “attack against them all.”

Furthermore, the U.S. president does not have the power to unilaterally withdraw the country from NATO.

“I can’t imagine any other American president of either party since the establishment of NATO saying such a thing,” Cheney continued. “It’s completely uninformed and ignorant and dangerous.”

During her interview, the retired Republican legislator also told Tapper she was worried by where Trump’s sympathy to Russia may lead the Republican Party as a whole.

“We have to take seriously the extent to which you’ve now got a Putin wing of the Republican Party,” she said, calling it critical to keep that faction out of the West Wing.

See Cheney’s full interview below: