Hours after Iran shot down a U.S. drone in what Iranians say was a "clear message" to the United States, former Vice President Joe Biden slammed President Trump's foreign policy as a "self-inflicted disaster" in which the president is "failing" to prevent Iran from obtaining and sustaining nuclear capabilities.

Biden issued a laundry-list of items where he says the president has dropped the ball on Iran, including his campaign promise to withdraw from the Obama-era Iran nuclear agreement.

"Trump promised that abandoning the deal and imposing sanctions would stop Iran's aggression in the region. But they've only gotten more aggressive. Trump also promised that walking away would somehow lead to a better deal – instead, the predictable has happened: Iran is building back up its nuclear capability. It's sadly ironic that the State Department is now calling on Iran to abide by the very deal the Trump Administration abandoned," Biden said.

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He added, "By walking away from diplomacy, Trump has made military conflict more likely. Another war in the Middle East is the last thing we need."

The Trump campaign responded to Biden's claims, calling into question Biden's move in "attacking" Trump in response to Iran's provocations.

Iran shoots down an American drone in international airspace, and Joe Biden’s response is to attack President Trump? What is his solution? Send Iran more pallets of cash? Let Iran take more U.S. sailors hostage? More coddling? — Official Trump War Room (@TrumpWarRoom) June 20, 2019

Biden meanwhile urged leadership that takes "strategic action to counter the Iranian threat" while emphasizing the value "principled democracy" has in restoring the U.S.' standing on the world stage. The former vice president has long criticized Mr. Trump's foreign policy agenda, previously claiming the president's approach "endangers" America's interests.

"This administration casts global affairs in a dog-eat-dog competition," Biden said in October. "It's this brand of zero-sum thinking that I find the most disturbing and dangerous."

His comments come as U.S. officials say Iran shot down an American spy drone over international waters over the Strait of Hormuz. Iran, however, claims it shot down the drone flying in its airspace, and has condemned the alleged "provocative" act and warned of unspecified retaliation.

The drone was shot down hours after Iranian-backed Houthi rebels in Yemen fired a missile into neighboring Saudi Arabia, a key U.S. ally in the Mideast. Both incidents come amid soaring tension in the region as the U.S. accuses Iran of multiple attacks on oil tankers.