President Joe Biden on Tuesday blasted comments about NATO by his likely 2024 election opponent Donald Trump, calling them “dangerous” and “un-American” and saying they raised the stakes for the U.S. Congress to approve new funding to support Ukraine.

At the White House, the Democrat sharply rebuked Trump’s comment over the weekend calling into question U.S. willingness to support members of the Western defense alliance if they were attacked.

Biden said Trump’s comment made it more urgent that congress pass his long-stalled funding request to support Ukraine’s defense against Russia.

“The stakes were already high for American security before this bill was passed in the Senate last night,” he said. “But in recent days, those stakes have risen. And that’s because the former president has sent a dangerous and shockingly, frankly un-American signal to the world.”

On Saturday, the Republican Trump complained during a political rally in South Carolina about what he called “delinquent” payments by NATO members and recounted what he said was a past conversation with the head of “a big country” about a potential attack by Russia.

“No, I would not protect you. In fact I would encourage them (Russia) to do whatever the hell they want. You gotta pay,” Trump said he told the unnamed leader.

In remarks calling for Republican Speaker Mike Johnson to bring a Senate-passed $95.34 billion military aid package for Ukraine, Israel and Taiwan to a vote in the House of Representatives, Biden said of Trump’s comments: “For God’s sake, it’s dumb, it’s shameful, it’s dangerous, it’s un-American.”

Biden said failing to support Ukraine war funding would amount to support for Russian President Vladimir Putin, adding that his attacks may move beyond Ukraine’s borders deeper into Europe.