Former US Secretary of Defense Robert Gates stated on Thursday that Washington must make it clear to Israeli leaders that the US must not permit Israel to harm American interests.

Speaking at an event in Norfolk, Virginia, Gates commented that the Israeli leaders must be aware they "do not have a blank check to take action that could do grave harm to American vital interests."

Instead, Gates called for heavier sanctions on Iran, saying the "results of an American or Israeli military strike on Iran could, in my view, prove catastrophic, haunting us for generations in that part of the world."

He added sanctions are "our best chance going forward, to ratchet up the economic pressure and diplomatic isolation to the point where the Iranian leadership concludes that it actually hurts Iranian security and, above all, the security of the regime itself, to continue to pursue nuclear weapons."

Gates also warned that neither Israel nor the US has the capabilities to obliterate Iran's atom program, and that a military operation against the country's nuclear facilities "would make a nuclear-armed Iran inevitable."

He inferred that any attack would see Iran merely "bury the program deeper and make it more covert.”

Gates' comments follow his criticism of Prime Minister Binyamin Netanyahu last month, where the newly retired defense secretary called him an ungrateful ally and blamed him for diplomatically isolating Israel and hurting American interests,  as Bloomberg revealed.

The criticism, reported in a piece by Jeffrey Goldberg, apparently peaked after Netanyahu met with US President Barack Obama last May, lecturing him in front of the cameras on the Israeli security situation with a level of "impudence" that shocked many in the White House, including Secretary of State Hillary Clinton.