Israel's army conducted a bridge-laying exercise across a river -- in this case the Jordan -- under fire a few days ago, the first such exercise in five years.

It's a pointer to the growing military preparedness that's been under way in recent months in Israel, with growing emphasis on special operations and swift, deep penetration into hostile territory.

The Jerusalem Post's military specialist, Yaakov Katz, observed that the exercise was "a sign of the type of future conflicts Israel is facing."

The bridge-laying operation included Merkava-4 tanks with infantry troops and elements of the Combat Engineering Corps using advanced assault bridging systems developed by state-owned Israel Military Industries.

The military declined to say what objectives might be involved in such operations.

But Brig. Gen. Agay Yehezkel, until recently commander of Division 162 which participated in the exercise, said, "This is a major operational challenge that exists on a number of fronts and could even catch us in places we don't expect to be."

In recent months, Israel's armed forces have been undergoing major upgrading amid a transformation of their military doctrine, which has traditionally placed great emphasis on conventional armored divisions and large maneuver formations with intense firepower supported by a strike-oriented air force.

But, like U.S. forces with whom the Israelis constantly have joint exercises, the trend is increasingly away from the big battalions to highly mobile and agile special operations, often conducted inside hostile territory.

Within this concept, in December Lt. Gen. Benny Gantz, the Israeli chief of staff, unveiled the formation of Deep Corps, a strategic Special Forces command, similar to the U.S. Special Operations Command that's fast extending global reach.

The new unit's mission is deep penetration in hostile states, presumably including Iran, Syria and Lebanon, and possibly Egypt sometime in the future.

Establishing such a force has been under consideration for some time.

"What has changed," the Post observed, "is the nature of the threat that Israel faces, which requires elite units to operate far from Israel and deep within enemy territory."

Deep Corps integrates all Israel's Special Operations units, including the army's elite Sayaret Metkal, the navy's Flotilla 13 and the air force's Shaldaq target designation team, into a single command.

Deep Corps would mount larger scale operations involving a variety of units outside their normal chain of command.

These could include taking out Hezbollah's long-range missile sites in northern Lebanon, or similar targets inside Syria to curb missile attacks on Israeli cities, the main Israeli concern at this time.

Israel's military planners believe Iran, Syria, Hezbollah and Palestinian militants now have some 62,000 missiles and rockets for an unprecedented bombardment of Israel's cities and strategic installations.

Defensive anti-missile systems have been developed, a process accelerated after the 2006 war when Hezbollah hammered northern Israel with some 4,000 missiles and rockets in 34 days.

Most launch sites can be taken out from the air but others would require ground attacks. This has given impetus to developing new weapons systems for deep-penetration forces.

Maj. Gen. Sami Turgeman, the ground forces commander, disclosed recently the army was looking into developing a miniature version of the Iron Dome missiles system designed to intercept short-range rockets and mortar rounds. These could be carried by Special Forces operating in hostile territory to counter rocket attacks.

Meantime, the military command's putting the final touches to a new five-year defense plan that incorporates procurement, training and operational doctrine. The plan, known as "Oz" -- Hebrew for "strength" -- should take effect at the end of the year once it's approved by the General Staff.

Israel is facing threats of varying degrees of immediacy in Syria, Iran, Lebanon, the Gaza Strip and Egypt.

The most pressing issue is whether Israel, ignoring U.S. warnings, will launch pre-emptive strikes against Iran's nuclear facilities, an assault that will likely trigger a regional war.

Whether or not a diplomatic solution to Iran's nuclear project is found, Israel fears Iran will continue clandestine efforts to acquire nuclear arms.

"Israel will be looking at a situation more like the one in Iraq following the air force's strike at the Osirak reactor in 1981," Katz observed.

"The airstrike set back Saddam Hussein's attempt to obtain a nuclear capability but it wasn't until the first Gulf War a decade later that he was stopped for good."