Actually, it was 30 minites not 15, second: it was in the air long enough to acquire ELINT signatures of the Dimona nuclear reactors air defenses and the American X-band radar station linked to the US X-band station in Turkey, third: it was not ordered shot down until the political comcideration was bucked up to Bebe. Time enough for the Hizballah to have detonated a nuke gained from Iran.
In the US and F-16 on hot ramp alert can't get from Mass to NYC in that time. Throw in target acquisition time and ROEs that give permission for shootdown and I doubt we could effectively respond in 45 minute to an hour.
The problem for Israel is that their country is so small that 15 minutes makes a critical difference.