President Joe Biden was wrong to say the United States would not back an Israeli strike on Iran's nuclear program, his predecessor and potential successor Donald Trump told Fox News on Thursday.

The remarks highlight the difference between a dovish Democrat administration that has sought to tamp down on Mideast tensions and Trump who has repeatedly hit at Iran during his tenure.

Asked following Iran's biggest ever attack on Israel on Tuesday, which involved nearly 200 ballistic missiles but was largely repelled with US help, whether Israel should hit back and Iranian nuclear sites, Biden said "no."

That was “not the right answer,” Trump told Fox News.

“I mean, that’s the craziest thing I’ve ever heard. That’s the biggest risk we have. The biggest risk we have is nuclear ... Soon they’re going to have nuclear weapons. And then you’re going to have problems.”

Trump earned the ire of the Islamic Republic when he unilaterally withdrew from an international deal over Iran's nuclear program in 2018 and by ordering the assassination of one of its top commanders Qassem Soleimani in a drone strike in Baghdad in 2020.