WASHINGTON – President Barack Obama delivered his most explicit threat yet that the United States will attack Iran if that’s what it takes to prevent it from developing a nuclear bomb. At the same time, he warned Israelis they would only make a bad situation worse if they moved pre-emptively against Iranian nuclear facilities.

The double-barreled warning, in an interview published Friday, came before Obama’s high-stakes meeting with Israeli Prime Minister Benjamin Netanyahu on Monday and a speech Sunday to the American-Israel Public Affairs Committee, a powerful pro-Israeli lobby. Obama said an Israeli strike would stir sympathy for the Islamic republic in a region where it has few allies. But he made clearer than before that Iran could face attack from the United States.

“I think both the Iranian and the Israeli governments recognize that when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say,” Obama told The Atlantic magazine. “I don’t bluff.”

He said Iran and Israel both understand that “a military component” is among a mix of many options for dealing with Iran, along with sanctions and diplomacy, making plain a threat to attack that had previously been more subtly implied.

The warning reveals how the threat that Iran could pose to Israel has eclipsed every other issue in the close but often contentious U.S. relationship with Israel, and raised the political stakes for Obama. Iran’s disputed nuclear ambitions dwarf the unfinished business of peace with the Palestinians and Obama’s sometimes testy relationship with Netanyahu.

The White House dispute with Israel is about the risks versus the benefits of a military strike in the near term, not whether one is ever appropriate. The issue is infused with domestic politics in both the United States and Israel, and Obama is at pains to show American Jewish voters that he is not being harder on Israel than on Iran.

“Every single commitment I have made to the state of Israel and its security, I have kept,” he said in the magazine interview. “Why is it that despite me never failing to support Israel on every single problem that they’ve had over the last three years, that there are still questions about that?”

Obama then suggested an election-year answer to his own question, accusing Republicans of trying to fan the doubts and slam a wedge “between Barack Obama and a Jewish-American vote that has historically been very supportive of his candidacy.”

He firmly rejected the notion that the United States might settle for a strategy of letting the Iranians build a nuclear weapon but deterring them from using one.

“You’re talking about the most volatile region in the world,” he said. “It will not be tolerable to a number of states in that region for Iran to have a nuclear weapon and them not to have a nuclear weapon. Iran is known to sponsor terrorist organizations, so the threat of proliferation becomes that much more severe. “

Israel has been publicly debating whether to launch air strikes on Iran’s known nuclear facilities in the next several months, before Israel judges that Iran’s program would be too far along to stop. The Obama administration argues that the time for a strike is farther away, and that there is still time to persuade Iran’s leaders to back down.

Israel wants U.S. backing for any military action against Iran, but has signaled it would go it alone if need be. Israeli officials have said they have made no decision yet, but the Obama-Netanyahu meeting comes amid a growing sense in Israel and in Washington that a strike is likely.

Israeli officials appear unmoved by the U.S. arguments, and Obama is unlikely to talk Netanyahu out of launching a strike if the Israeli leader decides not to wait.