For several hours after an arms convoy evaporated on Wednesday, denial ruled: Syria and Lebanon insisted nothing had happened along their mutual border, and Israel, unusually, maintained complete radio silence. Not a single politician even hinted that he might have a clue about what did or didn’t happen.

Had it not been for the international media, it’s doubtful the veil would have been lifted. But at 10 A.M., Arab websites began reporting that the Israel Air Force had been unusually active in the skies of Lebanon overnight. At about 2 P.M., Reuters quoted Western intelligence sources confirming that Israel had carried out an attack. And at 6 P.M., the Associated Press offered more details: Israel, it said, had bombed an arms convoy on the Syrian side of the border not long after midnight. The convoy, the news agency reported, was carrying Russian-made SA-17 missiles that Syria was trying to transfer to Hezbollah.

If so, the attack was presumably carried out by fighter jets carrying precision weapons: Hitting a convoy requires operational precision, as well as an impressive level of intelligence about events in Syria and Lebanon.

If such an attack indeed occurred, Israel is evidently trying to avoid retaliation by repeating the tactics it used between September 2007 and summer 2008, when it was widely thought to be behind three other operations in Syria: the bombing of a nuclear reactor, the assassination of Syrian Gen. Mohammed Suleiman, who was involved in both Syria’s nuclear program and its ties with Hezbollah, and the assassination in Damascus of Imad Mughniyeh, Hezbollah’s operations chief.

In each of these cases, Israel refused to claim responsibility. The reasoning was that as long as Israel didn’t claim responsibility, it would be possible for Syrian President Bashar Assad to deny that anything happened, and therefore he wouldn’t feel obliged to respond.

But Assad’s position is now incomparably worse than it was then. He’s fighting for his life and that of his regime against opposition groups that have already taken over about 75 percent of Syria. An Israeli attack, if there was one, is the least of his worries. So it seems unlikely that Israel is worried about a Syrian response.

Rather, the critical question is what Hezbollah − which has yet to make any public comment about the incident − will do. Over the past year, Israel has worried that its deterrence against Hezbollah was eroding, after six years of quiet following the Second Lebanon War. Though the organization hasn’t launched any direct attacks along the northern border, it was behind the bombing of a bus full of Israeli tourists in Bulgaria in July and sent a drone into Israel in October. These are signs that it is prepared to take greater risks than in the past.

On the other hand, Hezbollah, too, is worried by the precarious state of its patron in Damascus. Nor is its patron in Tehran likely to want a Hezbollah-Israel war at a time when the international community is mulling tougher sanctions against Iran’s nuclear program.

Interestingly, neither Western nor Arab countries have denounced the alleged Israeli attack: Most of them are rooting for Assad to fall.

Israel has repeatedly detailed its red lines on Syria and Hezbollah. As far back as 2008, long before the Syrian uprising began, the Olmert government warned that it wouldn’t tolerate the transfer of “game-changing” weapons to Hezbollah. Subsequently, it elaborated on what that meant: no anti-aircraft missiles, anti-ship missiles or long-range precision surface-to-surface missiles.

According to Western intelligence sources, these warnings were effective for a time. But it’s also possible that Syria and Hezbollah managed to smuggle in such weapons undetected by Israel: There have been unconfirmed reports that Hezbollah has precision, long-range M-600 rockets and also long-range Scud B and D missiles.

Recently, there has also been concern that the embattled Assad regime might send chemical weapons to Hezbollah. But that is a taboo he would think long and hard about breaking.

A transfer of conventional anti-aircraft missiles, in contrast, seems highly likely − a worry seemingly confirmed by Wednesday’s AP report. Israel is particularly concerned about the Russian-made SA-17s because they could substantially restrict the IAF’s freedom of movement over Lebanon − an area where today, it can operate virtually unhindered. These IAF flights are crucial for gathering intelligence about Lebanon.

Over the past week, the Israeli media has been full of renewed Israeli warnings against such a transfer. So if Syria and Lebanon nevertheless attempted it, why did they? One reasonable guess would be that Assad feared the rebels were about to overrun one of his arsenals, so he decided to try to smuggle the weapons out under cover of the stormy weather that has blanketed the north for the last few days. Alternatively, it could be that Hezbollah made the attempt because it deems the Assad regime nearer collapse than commonly thought.

On Wednesday, the northern border was quiet, but tensions remain high. Chief of Staff Benny Gantz is planning to leave for Washington later this week.

The fact that almost 24 hours have gone by with no response from Hezbollah could be seen as encouraging. But it’s hard to predict whether the organization’s restraint will last. If, contrary to expectations, it decides to respond forcefully, this will be a very different war than November’s operation in Gaza: Hezbollah’s ability to hurt the Israeli home front is much greater than that of Hamas.

The bigger problem is that this wasn’t a one-time event: The worse Assad’s position grows, the more attempts Hezbollah will make to grab whatever weapons it can get its hands on. And it seems Israel, if it was responsible for the air strike, has made its red lines clear. Thus the tensions in the north are liable to persist for a long time to come.