JERUSALEM (AP) - The threat from Iran dwarfs all other challenges the Jewish state faces, Israel's prime minister declared Sunday, as high-level hints of a possible Israeli attack on Iran's suspect nuclear program mounted.
One indirect indication came Sunday, when Israel's military began sending mock text messages to cellphones warning of incoming missiles, part of a nationwide experiment that is to continue through Thursday and reach hundreds of thousands of cellphone users. Last week, defense officials confirmed that Israel's top-tier missile defense system has been upgraded.
"All threats directed at the Israeli home front are dwarfed by another threat, different in its magnitude and substance, and so I have repeated and shall repeat: Iran must not be allowed to obtain nuclear weapons," Prime Minister Benjamin Netanyahu told his Cabinet on Sunday.
The prime minister's opening statement at the Cabinet meeting is open to reporters, providing him with a channel for a weekly public message.
Skeptics say Israel is rattling its sabers as part of a diplomatic campaign but would hesitate to actually attack Iran, because of the real possibility that it could trigger an all-out war targeting Israel from several directions at once.
Tehran insists its nuclear program is peaceful and designed to produce energy and medical isotopes, but Israel, like much of the international community, thinks it could be a cover to build bombs.
Netanyahu said earlier this month that Israel has not decided whether to launch an attack. But he and other leading Israeli officials have noted that tough international sanctions have not pressured Iran to abandon its suspect uranium enrichment program - a process that has civilian uses but could also be used to build bombs.
Some senior officials have suggested in the past that Israel cannot wait beyond early fall to strike, as Iran moves key facilities into fortified underground bunkers out of the reach of Israeli bombs.
Over the weekend, a senior "decision-maker" widely identified as Defense Minister Ehud Barak was quoted by an Israeli newspaper as saying that "the sword hanging over our neck today is a lot sharper than the sword that hung over our neck" before the Jewish state went to war with three Arab nations in 1967.
Although Israeli leaders haven't explicitly threatened to attack, they have been saying for years that they would not tolerate a nuclear Iran, and "all options are on the table." The U.S. has a similar policy.
Standing beside U.S. Defense Secretary Leon Panetta earlier this month, Netanyahu warned that time was quickly running out to stop Iran from achieving nuclear capability.
The United States has said it would be prepared to use military force to prevent Iran from becoming a nuclear power. But with its superior firepower, it could wait longer than Israel could to strike at Iran's underground facilities, and experts have judged Washington has more than a year to act.
Another factor in the timing could be the U.S. presidential election in November, where a Mideast flare-up sending oil prices soaring could harm President Barack Obama's re-election chances.
White House spokesman Jay Carney said over the weekend that Obama "remains committed to preventing Iran from acquiring a nuclear weapon," but that the U.S. still thinks there is time to persuade Iran through sanctions and diplomacy.
While Netanyahu and Barak have concentrated on the perceived nuclear threat, critics of an attack - including a recently retired spymaster and onetime internal security chief - have warned of its repercussions.
At best, they say, Israel could set back Iran's nuclear development for two to three years, and at worst, trigger a harsh retaliation from Iran and its proxies in Lebanon and Gaza - and possibly set off a region-wide war.