...then isn't it a little late for dithering about involvement in a conflict?

At a minimum, removing the artillery pieces on the other side would seem appropriate.

Should have thought things through before they did that.

Bitching at Syria for errant shells is a little bit chutzpah dontcha think.

I don't find it unusual that a democracy like Turkey might take exception to a neighbor (even a previously friendly one) violently repressing massive peaceful protests. You may be of the opinion that what the dictator next door does to his citizens is none of my business. As long as their misery stays within their borders, what do I care? (The "national sovereignty trumps human beings" philosophy.)

Others do not agree. Turkey chose not to sit and watch as Assad's military provoked a civil war and then went all out to win it. You are right that Turkey should expect some blowback from supporting the Syrian opposition. Perhaps they were surprised that Syria shelled Turkish territory. Perhaps not. Either way Turkey doesn't want shells falling on its territory any more than Syria wanted that Turkish jet flying over Syrian territory back in June.

Turkey may have a nice facade but the are just as repressive as any other dictator.

Ask a Kurd.

a Catholic in Northern Ireland? Ask a Basque? Ask a Native American?

Turkey is not better than those places, but there has been also some progress during current admin against the military oligarchy.