Defense Minister Ehud Barak warned Wednesday that Jerusalem is "committed to doing everything it can in order to stop Iran from going nuclear."
I am "fully aware of the difficulties and complexities involved in preventing Iran from attaining nuclear weapons," Barak told graduates of the IDF National Security College.
Israel is facing "difficult and fateful decisions" in weighing methods to stop Iran's controversial uranium enrichment program, he said.
Iranian officials contend that their program has only peaceful goals, but officials in Jerusalem, the West, and Gulf Arab states say Iran is pursuing nuclear weapons.
Barak said "having to deal with the challenge" of an Iran possessing nuclear bombs "would be many times more complex, dangerous and costly, both in terms of human life and in terms of resources, than a preemptive strike."
"But a look at the facts leads us not only to avoid reconsidering our calculations, but to move on our intended path with greater confidence," he added.
Barak added: "the Iranians are determined to continue deceiving the entire world, in order to achieve nuclear weapons. Whoever wants proof just needs to look at the talks over the last few months, including the most recent talks in Moscow."
He termed Iran's nuclear program "a unique challenge" to Israel "with the potential to develop into an existential threat."
Barak said Israel would remain responsible for its own security, rather than depending on other states, such as the United States.
Referring to the last two years of tumultuous changes in the region, Barak said the so-called Arab Spring "has slowly become an Islamic Summer," a development that "teaches us that in the moment of truth, we can only rely on ourselves."
The defense minister insisted that "America understands that the government of Israel -- and it alone -- holds the ultimate responsibility of the decisions that affect the security and future of the State of Israel."
Barak previously referred to several failed rounds of recent diplomatic talks between the world powers and Iran aimed at ending Tehran's uranium enrichment efforts as "an illusion."
Wednesday's remarks by Israel's top military official come on the heels of recent statements by Iranian President Mahmoud Ahmadinejad that "There are currently 11,000 centrifuges active in enrichment facilities."
The number is 1,000 higher than the May estimate of the International Atomic Energy Agency, which has gone on record saying that it suspects Iran is seeking nuclear weapons related technology.
"Iran isn't telling us everything," IAEA chief Yukiya Amano charged earlier this year, noting Iran continued to impede inspection efforts by the world nuclear watchdog.
Tehran, as a signatory to the Nuclear Non-Proliferation Treaty, is obligated to allow full acess to its nuclear facilties to IAEA inspectors.