JERUSALEM, Sept. 1-- Israel and the United States are confronting new challenges posed by a "chronically unstable" Middle East, Israeli Defense Minister Moshe Ya'alon on Monday told a visiting delegation of the U.S. House Foreign Affairs Committee.

"In this tough neighborhood, we are meeting new challenges that include all the varieties of radical Islam, whether it is ISIS, Hamas, Hezbollah, al-Qaida elements on the Golan Heights and over the border," Ya'alon said, contending that the "Iranian threat" is the central factor behind the instability plaguing the region.

The remarks came a day after the Israel Air Force shot down a drone that entered Israeli airspace in the northern Golan Heights, and as intense battles between Syrian government forces and rebels for control of a strategic crossing adjacent to the border with Israel continued into Monday.

Israel will not allow any breach of its sovereignty on the Golan Heights or at any other of its borders, Ya'alon told the U.S. delegation, which includes Representative Ed Royce, a California Republican who chairs the House Foreign Affairs Committee, and ranking member Eliot Engel.

During their meeting with Ya'alon at the Defense Ministry in Tel Aviv, the congressmen were briefed on the Israeli military's operations in the recent war with Hamas and the militant group's " usage of Gaza's civilian facilities to fire rockets at Israel and its residents as human shields," the ministry said in a statement.

Ya'alon, who had previously come under fire for criticizing the Obama administration's handling of Mideast crises, including a failed nine-month attempt to broker peace between Israel and the Palestinians, told the delegation that their visit "reflects the closeness and alliance" between the two countries, which is based on "shared interests and values."

He said Israel greatly appreciates the military aid from the United States, noting the "special relations" between the Pentagon and his ministry, and between himself and his counterpart, Secretary of Defense Chuck Hagel.

"We share our views with regard to events in the Middle East," said Ya'alon, adding that both he and Hagel also believe that Washington and Jerusalem will know how to join forces in dealing with the challenges they present.

Congressman Royce said the delegation's visit was an expression of solidarity with Israel and intended to discuss joint challenges in combating terrorism.

He said the United States derives "great satisfaction" from the recent success of Israel's Iron Dome rocket defense system in intercepting hundreds of rockets fired from Gaza at Israel during the course of the 50-day conflict.

"Without Iron Dome, without the joint effort of the United States and Israel, and the support from Congress, Israel wouldn't have attained the results it did," said Royce.