Israel's air force is expected to take delivery of advanced Arrow-2 missiles interceptors, capable of greater killing power against Iranian and Syrian ballistic missiles, over the next few weeks amid rising Middle East tensions.

The disclosure of the deployment of the upgraded Arrows, known as the Block 4 variant, to bolster the top tier of Israel's multilayered missile defense shield, came hard on the heels of an announcement by the Islamic Republic it had tested a fourth-generation model of the solid-fueled, short-range Fateh-110 missile with a new guidance system.

That followed the reported successful test-firings of two Iranian long-range missiles during a recent naval exercise in the Persian Gulf, where Iran is locked in a military confrontation with the United States over Tehran's refusal to abandon its nuclear program.

"The new Israeli developments ... should be viewed as part of the complex campaign currently conducted between Israel, Iran and Hezbollah," analyst Amos Harel wrote in the Israel Haaretz daily Sunday.

"Just as Syria and Iran are flexing are flexing their muscles, demonstrating missile and rocket launching capabilities in frequent training exercises, Israel has decided to publicly announce the fact that is has significantly upgraded its defense systems."

Last week, the regime in Syria, battling an 18-month-old uprising against President Bashar Assad, admitted for the first time that it has an arsenal of chemical and biological weapons.

Missiles and rockets are seen as the primary delivery system for these weapons but they can also be fired in large-caliber artillery shells.

The long-range, high-altitude Arrow 2 is built by Israel Aerospace Industries, state-owned flagship of Israel's defense industry. An even more advanced Arrow-3 variant is being developed by IAI and the Boeing Co.

The plan is for it to intercept missiles outside Earth's atmosphere, higher in their trajectory toward Israel at double the operational altitude of Arrow-2, and cope with multiple re-entry warheads, while ignoring decoy warheads.

The exoatmospheric, two-stage Arrow-3, highly maneuverable with capabilities similar to those of the U.S. Navy's Aegis counter-missile system, is slated for operational deployment in 2014.

The core of Arrow-3's technological development is the two-stage propulsion unit.

The first engine hoists the missile past Earth's atmosphere and then separates. The smaller maneuvering missile continues with its own power unit.

It carries a sophisticated electro-optical homing warhead that "sees" a very wide spectrum of in flight and allows for very high maneuverability.

It can be diverted from one target to another and shortens the interception period, which Israel Defense magazine noted is "a vital factor in the defense concept, especially in the event of a missile barrage."

Arrow-3 has another advantage: it can be launched from advanced missile ships as well as land facilities.

The United States recently pledged nearly $1 billion for development of Arrow-3 and other Israeli counter-missile systems.

These are now at the top of Israel's defense priorities because of the overarching threat that Iranian and Syrian missiles, as well as rockets held by Palestinian militants and Hezbollah in Lebanon, now pose to the Jewish state.

Hezbollah alone is reported to have more than 43,000 missiles and rockets provided by Iran and Syria. That's nearly four times the number it had at the start of its 34-day war with Israel in 2006.

Israel Defense says Washington now provides around 80 percent of the development and production costs for Arrow-3, with Israel covering the rest.

Once Arrow-3's operational, each missile will cost around $2 million-$3 million per unit.

"The design of Arrow-3 promises to be an extremely capable system, more advanced than what we have ever attempted in the U.S. with our programs," said Lt. Gen. Patrick O'Reilly, director of the U.S. Missile Defense Agency.

The Jerusalem Post reports that the Block 4 version contains new software that improves the missile's ability to counter ballistic weapons such as Iran's Shehab-3b -- the backbone of Tehran's strategic missile force -- and more advanced Sejjil-2 now being developed, as well as Syria's Soviet-designed Scud Ds.

In a series of tests, Arrow was able to intercept missiles with the flight profile of a Shehab-3 both day and night and all weather conditions.

Arrow-1 was initially deployed March 2000 and two batteries are operational. In July 2005, Israel and the United States successfully tested the Arrow against a captured Scud.