Ummm, doesn't this mean war?

Iran shelling targets deeper inside northern Iraq

So goes the headline on an wire service story. Iran is now shelling places 10 1/2 miles into Iraq. If Germany started to shell France or Mexico started to shell the US, war would be declared and if not full scale operations took place, at least the batteries doing the shelling would be silenced by counter battery or an air strike.

While Iran is saying it is shelling camps that support rebels operating in Iran and therefore the camps are legitimate targets, Iraq and the US can say Iran is supporting the insurgents in Iraq and therefore the Republican Guards and the Iranian leadership are fair game for US retaliation.

What is going on??