Rep. Alexandria Ocasio-Cortez, D-N.Y., blasted President Trump's decision to strike one of Iran's top military commanders, arguing that doing so risked war and the loss of millions of lives.

"Last night the President engaged in what is widely being recognized as an act of war against Iran, one that now risks the lives of millions of innocent people," she tweeted on Friday.

Her comments came as Iran vowed to retaliate over a U.S. airstrike that left Qassem Soleimani dead. Soleimani previously led the Quds forces within Iran's Islamic Revolutionary Guard Corps. In the aftermath of his death, the State Department told Americans to "immediately" leave neighboring Iraq due to the region's volatile circumstances.

Ocasio-Cortez pressed Congress to take action. "Now is the moment to prevent war & protect innocent people - the question for many is how, publicly & Congressionally," she said.

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She called on Congress to fulfill a "moral and legal obligation" to prevent war. "Congress now has a moral and legal obligation to reassert its power to stop this war and protect innocent people from horrific consequences," she said.

The New York congresswoman proposed that her colleagues vote on the War Powers Resolution, the Vietnam War-era legislation that requires the president to get Congressional approval before keeping troops in conflict for a set period of time. The law has been routinely flouted by previous administrations.

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She also promoted a resolution that would block money from flowing to offensive action against Iran. "This amendment passed the House w/ bipartisan support not long ago, and was later gutted in negotiations. We can bring it back as a standalone bill," she said.

Americans should ignore the "cheerleaders of war" and warned against "gaslighting," Ocasio-Cortez argued.

"Right now is the moment to decide if you are pro-peace or not," she tweeted. "The cheerleaders of war, removed from its true cost, will gladly convince you that up is down - just as they did in Iraq in ‘03. But war does not establish peace. War does not create security. War endangers us all."

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Her comments followed those of her fellow squad member Rep. Ilhan Omar, D-Minn., who similarly called on Congress to step in and prevent armed conflict with Iran.

Trump defended the decision, tweeting on Friday that "General Qassem Soleimani has killed or badly wounded thousands of Americans over an extended period of time, and was plotting to kill many more ... but got caught!"

"He was directly and indirectly responsible for the death of millions of people," he said.

The United States is sending nearly 3,000 more Army troops to the Mideast as reinforcements in the volatile aftermath of the killing of an Iranian general in a strike ordered by President Donald Trump, defense officials said Friday.

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Secretary of State Mike Pompeo defended the strike as “wholly lawful,” saying that Soleimani posed an “imminent” threat against the U.S. and its interests in the region.

“There was an imminent attack,” Pompeo told Fox News. “The orchestrator, the primary motivator for the attack, was Qassem Soleimani.”

The Associated Press contributed to this report.