"President Trump's Iran strategy is a self-inflicted disaster", Biden said in a statement. "By walking away from diplomacy, Trump has made military conflict more likely. Another war in the Middle East is the last thing we need. Trump promised that abandoning the deal and imposing sanctions would stop Iran's aggression in the region. But they've only gotten more aggressive".
Biden issued the statement as tensions soared between the two countries after Iran's Revolutionary Guard forces announced they had shot down a US Navy drone.
The US military's Central Command confirmed the downing, but said the aircraft was operating over the Strait of Hormuz, while Tehran insists that the drone crossed into Iranian territory in the coastal Hormozgan province.
Biden said the increasing tensions between the two countries stemmed from the fact that Trump pulled out of the Joint Comprehensive Plan of Action (JCPOA), the nuclear accord that former President Barack Obama's administration signed in 2015.
Trump unilaterally withdrew the US from the JCPOA and began re-imposing sanctions against Tehran in 2018. A year later, Iran responded by partially suspending its obligations under the agreement.
Relations between the US and Iran have become increasingly hostile since the US withdrawal from the accord. Over the past few weeks, the US has stepped up its military presence in the Middle East, citing "threats" from Iran.