The New York Times reports: After President Obama arrived in Israel, his first stop on Wednesday was to inspect an installation of Iron Dome, the antimissile system hailed as a resounding success in the Gaza conflict in November. The photo op, celebrating a technological wonder built with the help of American dollars, came with considerable symbolism as Mr. Obama sought to showcase support for Israel after years of tensions over Jewish settlements and how to curb Iran’s nuclear ambitions.

Unstated amid the good will, though, was an intensifying debate over whether Iron Dome’s feats of warhead destruction were more illusory than real.

Israeli officials initially claimed success rates of up to 90 percent. Michael Oren, Israel’s ambassador to the United States, hailed the antimissile system as the first to succeed in combat. Congress recently called the system “very effective” and pledged an additional $680 million for deployments through 2015.

But a growing chorus of weapons experts in the United States and in Israel say their studies — based largely on analyses of hits and misses captured on video — suggest that Iron Dome destroyed no more than 40 percent of incoming warheads and perhaps far fewer. Many rockets, they argue, were simply crippled or deflected — failures that often let intact or dying rockets fall on populated areas.

“They’re smart people,” Richard M. Lloyd, a weapons expert who has written a critique of Iron Dome for engineers and weapons designers, said of the system’s makers in an interview. “But the problems go on and on.”

Behind that skepticism lie the messy realities of combat, as well as a half-century of global antimissile failures. “No military system is 90 percent effective,” said Philip E. Coyle III, who once ran the Pentagon’s weapons-testing program and recently left a White House security post.

For Iron Dome, the performance issue is important, in part, because defense bears strongly on offense. Israel’s decision on whether to bomb Iran’s nuclear sites — as it has repeatedly threatened to do — could hinge on its estimate of the retaliatory costs, including damage inflicted by rockets fired from southern Lebanon and the Gaza Strip. [Continue reading…]