The U.S. Ambassador to Israel, Daniel B. Shapiro, Tuesday called on Egypt to honor its peace treaty with Israel and warned that the diplomatic window for Iran was "shrinking."

"Egypt must honor its peace treaty with Israel," Shapiro told a luncheon of the Israel, Britain and the Commonwealth Association in Tel Aviv. "We need to establish the principle that [political] parties cannot go to the polls with a gun in one hand and a ballot in the other." In a wide-ranging, 40-minute address that touched upon U.S. strategic, military and economic cooperation with Israel, Shapiro expressed solidarity with the one million Israelis in the country's central and southern region who were within range of last month's 10-day, 300-rocket barrage from the Gaza Strip.

"No other country in the world experiences that kind of challenge - to build bomb shelters in preschools and kindergartens," said Shapiro, who noted American funding for Iron Dome, Israel's mobile air defense system, and his government's plans to ask Congress to fund additional systems, adding, "It's an unthinkable challenge." Shapiro said military cooperation between Israel and the United States during the Obama administration had reached "unprecedented levels."

Turning to the subject of Iran, Shapiro said that while the United States preferred a diplomatic solution to the standoff over Iran's nuclear program "no options were off the table."

"The clock is ticking, and Iran must change course," said Shapiro, who maintained that a nuclear-armed Iran was not only "an existential threat to Israel," but "also poses a grave threat to the security of the United States, to our allies, to our forces in the region and throughout the world."