If you listen to the Pentagon and the White House, there is no viable military option in Syria—even American air strikes supposedly would be too dangerous because of Bashar Assad’s anti-aircraft defenses. The Israeli Air Force doesn’t seem to have gotten the memo, however.

For at least the second time since January, Israel attacked a target in Syria, hitting a warehouse in Damascus on Friday that apparently stored advanced Fateh-110 missiles shipped from Iran and intended for Hezbollah. In late January, Israel similarly struck SA-17 anti-aircraft weapons intended for Hezbollah. There are so-far unconfirmed reports of yet another Israeli air strike in Damascus on Sunday morning.

Israel is doing what it must to defend itself—to prevent Hezbollah from taking advantage of the current conflict to further enhance its already formidable arsenal of weapons aimed at Israel. Its neighbors know that Israel is a serious country that acts when threatened. Not so with the U.S. that has announced a “red line” over the use of chemical weapons in Syria but refuses to act even when that line has been crossed. Instead, administration officials are leaking word that the “red line” phrase was an off-the-cuff mistake by the president.

This is hardly a reassuring message, and one that regimes across the region are receiving loud and clear–including Iran that must now know that Obama’s threats to stop its nuclear program are ultimately toothless. Israel, no doubt, is getting the same message: Prime Minister Netanyahu must realize that he cannot count on American action to stop the Iranian program. As it showed in Syria, Israel knows that if it doesn’t act to defend itself, then no one will. That will make it much harder for Obama to dissuade Israel from striking the Iranian nuclear facilities. Credibility is a precious coin in international affairs and unfortunately the president is rapidly devaluing America’s currency in that arena.