The Iran nuclear crisis is far from over, but Tehran appears to have made a subtle blink – backing away from its threat a few weeks ago to close the Strait of Hormuz in response to escalating U.S. sanctions.

The softening of Iran’s position followed a warning by a U.S. emissary this month that any effort to close the strait would trigger a potentially devastating U.S. response. Clearly, Tehran got the message – with a top Iranian official Thursday publicly disavowing the earlier saber-rattling.

“Iran has never in its history tried to prevent, to put any obstacles in the way of this important maritime route,” Foreign Minister Ali Akbar Salehi insisted.

But in a sign Iran is pressing its broader nuclear program, Salehi warned nations not to put themselves in a “dangerous position” by allying with the United States.

What started the jitters was a statement in late December by Vice President Mohammad Reza Rahimi that Iran would close the strait if the West imposed new sanctions on Iranian oil. On Jan. 3, a senior Iranian admiral said his country’s navy had practiced closing the strait; he warned that the aircraft carrier USS John C. Stennis, which recently departed the Gulf, should not return. But U.S. intelligence quickly picked up signs that some Iranian leaders were unhappy with the blustering comments.

The foreign minister’s statements, taken with other developments, suggest that war fever over a quick confrontation at the strait is ebbing. There’s no progress yet on the core issue of Iran’s nuclear program, but the United States has clarified its “red lines” in the crisis, and Iran has indicated by its public response that it understands.

Another step back from the brink was Wednesday’s statement by Israeli Defense Minister Ehud Barak that any Israeli attack on Iran was “very far off.” Barak was expressing the consensus of the Israeli national-security establishment.

The American back channel to Iran is an intriguing new factor. U.S. officials won’t disclose the identity of the emissary, but they said the person delivered an oral briefing that included both the warning on the strait and the reiteration of U.S. interest in serious negotiations.

Explaining Iranian behavior is always a puzzle. But it’s possible that their recent statements are responses to economic sanctions that are beginning to have a serious impact. I wrote last week about how Iran’s biggest customers – including China and India – are beginning to reduce their oil purchases from Iran, and looking to Saudi Arabia to make up the difference.This oil-market squeeze has begun to produce a financial run at home, as Iranians scramble for dollars that are in short supply. According to The New York Times, the Iranian currency fell to its lowest level ever against the dollar Wednesday. The black market rate has fallen more than 50 percent in the last month, to 18,000 rials to the dollar compared to 11,000 to 12,000 in December.

Putting these elements together, one intelligence official who closely follows Iran explained: “Iran is deterred now from crossing the Rubicon and developing nuclear weapons.” This official says Iran wants to obtain all the necessary components of a nuclear weapon — but wait to cross the threshold until the moment is right.

What the Obama administration wants are verifiable safeguards that, while allowing Iran to have a civilian nuclear program, prevent any breakout to weaponization. President Obama summed up his goal in an interview with Time’s Fareed Zakaria: “The Iranians have a very clear path where they say, we’re not going to produce weapons, we won’t stockpile material that can be used for weapons. The international community then says, we will work with you to develop your peaceful nuclear energy capacity, subject to the kinds of inspections that other countries have agreed to in the past.”

This confrontation still has a long way to run, with significant dangers on all sides. But last week’s exchanges made clear, at least, that urgent messages are being sent and received between Washington and Tehran.

David Ignatius writes about foreign affairs for The Washington Post. He can be contacted at: davidignatius@washpost.com