Amid reports quoting sources “very close” to the prime minister that the likelihood of an Israeli strike on Iran is shrinking, Defense Minister Ehud Barak on Friday intimated that Israel must act before Iran’s nuclear program becomes impervious to assault, and warned that inaction could result in “grave consequences.”

Although, as a rule, war or military action should be avoided unless absolutely necessary, Barak said, there are instances “where it appears as though it’s not necessary to attack now, but you know that you won’t be able to attack later.” In such cases, the “consequences of inaction are grave, and you have to act.”

Barak, who used the same address to say he did not rule out the possibility that Israel would reoccupy parts of the Gaza Strip because of security concerns, was speaking at a conference at the Fischer Institute for Air and Space Strategic Studies in Herzliya.

Former IDF chief of staff Gabi Ashkenazi, also attending the conference, said the military top brass must participate in the decision-making process leading up to any possible war.

“Strategic decisions need to be made as part of a dialogue between the political and military leaderships before war,” Ashkenazi said. In that dialogue, he said, “objectives [are] weighed as being realistic or not.”

Like Barak, Ashkenazi did not specify that he was talking in the context of the debate about an imminent Israeli strike on Iran, but the subtext was clear. Barak has repeatedly indicated his conviction that hitting a would-be Iran sooner, despite the attendant complications, would be better in the long-run than having to confront a nuclear Iran. Ashkenazi and other ex-security chiefs have stated that they do not believe a resort to force is necessary at this stage — a position shared with the US political and military leadership.

Barak’s statements came a day after the Israeli media reported that sources “very close” to Prime Minister Benjamin Netanyahu said that the prospect of an Israeli attack on Iran’s nuclear facilities is becoming “less and less likely.”

Channel 10 reported on Thursday that Israel “will not attack Iran” this year, provided that President Barack Obama sets out his “red lines” and offers certain other promised assurances to Netanyahu at a meeting between the two tentatively scheduled for Thursday, September 27.

The station reported that the two leaders will meet the day after the Jewish High Holiday of Yom Kippur (which falls on September 26), when Netanyahu will be in New York to address the UN General Assembly.

“If Obama gives Israel the promised ‘red lines’ and his personal commitments, Israel will not attack Iran,” the report detailed.

On Monday, after the New York Times reported that the administration was considering setting out certain red lines that, if crossed by Iran in its nuclear drive, would trigger a resort to military force, Netanyahu welcomed the idea. “The greater the resolve and the clearer the red line, the less likely we’ll have conflict,” he said.

US efforts to dissuade Israel from a resort to force appeared to be continuing Thursday, with a visit by Admiral James A. Winnefeld, Jr., the vice chairman of the Joint Chiefs of Staff. Winnefeld met with Barak in Tel Aviv, having arrived in Israel earlier in the week for talks focused on Iran and other defense issues, on a trip that was initially kept secret.

After their talks, Barak said the US and Israel “face the same challenge [on Iran] but the clocks are ticking at different paces.” He said “Israel reserves the right to make sovereign decisions. The US respects this. Israel and Israel alone will take the decisions that affect its future and its security.”

Later Thursday, even Barak issued rare praise for American efforts to deal with Iran. At a meeting of his Independence party, he spoke of the “impressive scale of American preparations to grapple with the threat.”

Winnefeld visited an Iron Dome anti-missile battery near Ashkelon Wednesday and, as a guest of IDF Deputy Chief of the General Staff Maj. Gen. Yair Naveh. He also took part in security meetings that addressed “the cooperation between the two armies,” Army Radio said Thursday.

Also Thursday, former MK and minister Tzachi Hanegbi, who in July left the Kadima party to re-join Likud, said in an interview with Makor Rishon that Israel is now “in the most fateful 50 days in Israeli history since the Yom Kippur War.”

Hanegbi, who used to head the Knesset’s Foreign Affairs and Defense Committee, said that every decision that Benjamin Netanyahu must make will come at a price. “The practical result of accepting a nuclear Iranian will be a nuclear arms race throughout the entire Middle East,” Hanegbi warned.

Last Thursday, General Martin E. Dempsey, the chairman of the US Joint Chiefs of Staff, said rather scathingly that Israel had the power to “clearly delay but probably not destroy Iran’s nuclear program.”

He also warned about the counter-productive consequences of such a strike, and took the highly unusual step of adding, “I don’t want to be complicit if they choose to do it.”