For the first time, Israel’s David’s Sling missile defense system was put into operational use on Monday morning, in response to the detection of 9k79 missiles fired in southern Syria. The David’s Sling failed to intercept either missile.

The 9k79 missiles, the Russian Tochka short-range ballistic missile, were fired against targets in ISIS-held territory in southwestern Syria. Israeli Army officials mistakenly thought that the missiles were going to land in Israeli-occupied territory.

Israeli officials defended the use of the David’s Sling, even though the missiles weren’t actually going to land in Israel, as an attempt to “minimize risk,” saying that the missiles carry substantial explosive payloads and it was better not to risk them hitting.

This has been a recurring problem for nations with substantial investments in interceptor missiles. The costly missiles have tended to perform poorly in even the most favorable tests, and using them against perceived threats, as today, risks very public failures, which is exactly what happened.

Israel not only spent massive amounts developing the failed missile system, but got Congress to chip in hundreds of millions of dollars as well. The US had been claimed to be interested in buying such missiles from Israel, though it’s not clear if that’s still the case at this point.