Israel is bolstering its military forces on the Golan Heights, its de facto border with Syria, against a possible attack by Hezbollah amid growing speculation Israeli warplanes or warships blitzed Russian-anti-ship missiles at the Syrian naval base of Latakia last week.

The base, in an area still held by the Damascus regime's forces in Syria's civil war, was hit by a series of mysterious explosions July 5.

There's been no confirmed evidence indicating the cause of the blasts. The rebel Free Syrian Army's Supreme Military Command said they were caused either by an air attack or a long-range missile strike from vessels in the eastern Mediterranean. That could only mean Israel.

The regime has been unusually silent about the explosions in one of its most secure areas, but Israeli Defense Minister Moshe Yaalon insisted Saturday the Jewish state's forces have not "intervened in the Syrian bloodshed for a long time."

He put no time frame on that, but stressed, "We have set red lines with regard to our own interests, and we keep them."

Israel apparently carried out airstrikes May 3 and May 5 against multiple military targets at Damascus International Airport, mainly storage facilities for F-110 Fateh surface-to-surface missiles reportedly bound for Hezbollah -- Syria's Iranian-backed Lebanese ally, which has thousands of fighters aiding the Damascus regime -- and similar targets east of the Syrian capital.

Israel has obliquely acknowledged the strikes, which apparently involved long-range stand-off missiles fired from Lebanese airspace, presumably to avoid Syria's Russian-built air defenses and to provide deniability.

Israel purportedly carried out a similar raid Jan. 30 against a convoy believed to be carrying Russian-built SA-17 anti-aircraft missiles to Hezbollah across the border in northeastern Lebanon, the Shiite movement's heartland.

The Israelis have been targeting Hezbollah surface-to-surface missiles and other advanced weapons, all provided by Iran or Syria, for some time because in any future conflict Hezbollah is expected to concentrate on waging a sustained long-range missile bombardment of Israeli cities and strategic targets, possibly for several weeks.

Under this strategic premise, Latakia would have been a target because, according to Israeli defense sources, that's where the Syrians have stored the 72 ship-killing P-800 Yakhont anti-ship cruise missiles, export version of Russia's Oniks system, they reportedly received from Moscow in 2011.

If the Israelis suspected Syrian President Bashar Assad was going to hand over some of these to Hezbollah, greatly boosting the anti-ship capabilities it first revealed during its 2006 war against Israel, it could be expected in the current highly charged climate to try to take these out in preventive strikes by air or sea.

Hezbollah seriously damaged an Israeli navy corvette off Beirut in the opening days of the 2006 war with a Chinese-designed C-802 anti-ship missile, provided by Tehran via Syria, and sank a passing Egyptian freighter.

The Yakhont is many times more deadly than the C-802. It can fly at mach 2.5, 2-1/2 times the speed of sound, has a range of 187 miles and carries a warhead of 550 pounds of high explosive.

Israel is still technically at war with Syria, but the two have not engaged in combat since the end of the 1973 war, when the Syrians came within an ace of recapturing the western sector of the Golan that Israel seized in the 1967 war.

Until the Syrian civil war erupted in March 2011, this was Israel's quietest border.

Israel fears the Golan front is becoming active again after 40 years. It's concerned jihadist rebels fighting Assad will target the Jewish state if the Syrian leader is toppled, or that Damascus will set Hezbollah loose there with advanced weapons.

There have been a few skirmishes along the cease-fire line in recent months. Hezbollah leader Hassan Nasrallah threatened in May to turn the Golan into a new front against Israel.

Now, an Israeli official disclosed, "our main concern is Hezbollah and the way it's building up its weapons arsenal ... We will respond with the relevant force-building to address that concern."

Israel has moved up tank reinforcements and advanced surveillance systems, and is reported to be upgrading the 366th division, a long-established reserve division, into a front-line combat unit to man the Golan line along with an armored division.