With Congress also lavishing cash on Iron Dome, some U.S. lawmakers have called on Israel to share that system, too.

The Israeli official said that though Iron Dome was different to Arrow as it was developed entirely by Israel, the current policy was to provide the Americans data upon request while a more permanent arrangement is negotiated.

In parallel to Arrow II, Israel is developing Arrow III, which is due to be operational in 2014 or 2015. Unlike previous generations of the interceptor, Arrow III will engage incoming missiles in space, using detachable warheads that, turning into “kamikaze” satellites, will seek out and slam into the target.

Israel is also working on a more powerful rocket interceptor than Iron Dome, known as David’s Sling or Magic Wand, which is due out next year. Meshed together and with U.S. counterparts, the three Israeli systems would form a multi-tier shield providing several opportunities to intercept incoming missiles.

(Adiitional reporting by Yeganeh Torbati in Dubai, Writing by Dan Williams; Editing by Anthony Boadle and Rosalind Russell)