With today's shooting down of a Russian SU24 by Turkey, the war in Syria just took a new twist - and one that sends a powerful message to the UK as it contemplates joining in bombing raids on Islamic State militants.
And for those who are hard of hearing, that message is: 'keep well out!'
Up until now, the war in Syria has looked complicated. On the one side the Syrian state led by President Bashar Assad, supported by its long term ally Russia, Iran and Iraq - 'Them'.
On another side, Islamic State (IS) and allied terrorist groups.