It would have been best for Obama to not threaten the Syrian government, and to not re-invade Iraq. Obviously I don't speak for all conservatives. The US needs to add to its Middle East presence by subtracting the negatives - Salafi Arabia and Iraq.
Do you mind expanding on "threatened Syria"? Re-invade Iraq? Do we have no obligation after we destablized the entire region after Bush Jr? Who was going to fight ISIS if we just left? Who was going to take a lead in trying to put the pieces back together?
Obama threatened the Syrian government, was called out, and cratered in to Russia's agreement. Also, the US has no obligation to Iraq or Afghanistan.