The apparent bombing run might have been akin to Israel's bombing of the Iraqi nuclear reactor at Osirak in 1981, if international media reports are to be believed.
For once, no one in the Israeli establishment is talking.
Based on government sources in the United States and elsewhere -- some of them named -- the reports suggest that on the night between Sept. 5 and 6, Israeli warplanes attacked a nuclear facility in northern Syria storing or processing nuclear materials provided by North Korea.
The presumed nuclear target would explain the secrecy shrouding the alleged Israeli operation. It also would explain the rumors of impending war between Israel and Syria earlier in the year, and the failure of the two countries to launch a peace process despite public expressions of willingness to do so.
According to the foreign reports, the story goes back to the beginning of the year and a secret meeting between North Korean and Iranian officials in the remote Korean border town of Ch'ongjin.
The North Koreans, having agreed to dismantle their nuclear weapons program in return for normalized ties with the West, were looking to sell off nuclear technology and materials the Iranians were only too willing to buy. The key material on offer was plutonium.
The reports imply that the Syrians long had wanted to acquire a nuclear weapons program of their own and, with North Korean help, they built a facility for plutonium processing and eventual weapons building.
According to the Washington Post, President Bush's national security adviser, Stephen Hadley, was presented in the spring with evidence of Syrian-North Korean nuclear cooperation. It included dramatic satellite imagery from Israel that led some U.S. officials to conclude the Syrians had built a facility that could be used to produce material for nuclear weapons.
At about the same time, Mossad chief Meir Dagan presented evidence to Israeli Prime Minister Ehud Olmert that Syria was seeking to acquire nuclear know-how from North Korea.
Dagan, according to the reports, feared the Syrians might be able to produce nuclear devices that could be installed on Scud-C rockets, which have the range to reach most points in Israel.
"This was supposed to be a devastating Syrian surprise for Israel," Sunday's U.K. Times quoted an Israeli official as saying. Had it gone through, Syria in a single stroke would have attained strategic parity with Israel.
While Hadley and Olmert supposedly were digesting the dramatic new information, Israeli and Syrian politicians started talking up the possibility of war in the summer.
At the time it was difficult to understand what had triggered the sudden threat of hostilities. Analysts spoke about rising tension between the two countries, but could not explain what was behind it.
The nuclear evidence theory provides a rationale.
In June, Israel's military intelligence gave the politicians a clear message: If there were no political negotiations with Syria soon, war was likely in the summer.
Olmert set up a special ministerial committee to monitor developments on the Syrian front. The United States, however, refused to give a green light for peace talks. In hindsight, some commentators now are suggesting the reason for this may have been Washington's awareness of Syria's nuclear plans.
The immediate spur for the Israeli strike may have been the arrival on Sept. 3 of a North Korean vessel at the Syrian port of Tartous. According to foreign sources, the Israelis believed the vessel was carrying nuclear materials, and this is what dictated the timing of the alleged Israeli strike on the night in question.
According to the London Observer, the strike was carried out by eight Israeli aircraft. Other reports suggested ground troops also had been involved, along with a high-flying reconnaissance plane.
Last week, two U.S. officials indicated there might be some truth to the nuclear theory.
Asked about the alleged Israeli airstrike -- Israel still refuses to confirm or deny it -- U.S. Secretary of State Condoleezza Rice said, "We have long been concerned about the proliferation of weapons of mass destruction."
Andrew Semmel, acting U.S. deputy assistant secretary of state for nuclear non-proliferation policy, told journalists in Rome last Friday that Syria, a state sponsor of terror, was on America's nuclear "watch list." He added that Syria may well have had contacts with secret suppliers, possibly North Korea. There are North Koreans in Syria, Semmel declared.
Syria and North Korea have strongly denied the nuclear cooperation story.
In an interview with Newsweek, Syria's ambassador to the United States described the reports as "absolutely, totally, fundamentally ridiculous and untrue."
According to Syria's original account of the incident, the Israeli planes were driven off by Syria anti-aircraft fire, fleeing hastily and dumping ammunition and fuel tanks in open fields.
Israeli officials are keeping quiet. Israeli journalists, including those writing for foreign news organizations, are subject to a military censor and have been reduced to piecing together foreign news reports.
In an appearance Sunday before the Knesset's Foreign Affairs and Defense Committee, military intelligence chief Maj.-Gen. Amos Yadlin was asked by the committee chairman, Tsachi Hanegbi of the Kadima Party, not to comment on the Syria story. Yadlin obliged.
Yadlin did, however, have a lot to say about Iran's nuclear ambitions.
He said Iran has no intention of aborting plans to produce a nuclear bomb. Iran has three messages for the West, Yadlin said: Iran already knows how to make nuclear devices; economic sanctions won't work; and military action against Iran will exact a very heavy price.
Assuming the Israeli strike against Syria did take place, the question now is what effect it will have on the Iran issue. Does this make a U.S.-led military strike on Iran more or less likely?
The answer to that question could well determine the historical significance of Israel's alleged action against Syria.
Leslie Susser is the diplomatic correspndent of the Jerusalem Report.