They cant do shit, its all about Turkey at this point, there is no need for agreements whatsoever, that was back then even those have not been kept by the americans and russians and now where these both are fighting a nasty proxy war u have again dynamics that heavily changed, Turkey has escalation dominance here and will use it and there is nothing they can do about it. Especially now where the russian armed forces have turned out to be a 3rd world army and the americans preparing for China invading Taiwan.
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There is Erdogan's full explanation about Syria, detailed and good information about the region, I recommend you to read it
“It is not possible for us to leave unanswered even the slightest attack against Turkey from the north of Syria. Certain terrorist organizations have focal points in northern Syria.
These focal points are present in all those regions, from northeast to northwest of Syria. Unfortunately, all coalition forces, especially the USA, are providing serious weapons, tools, equipment and ammunition to these terrorist organizations and they still continue to do so.
The USA gave these aids to thousands of trucks. Who is he doing? PKK, YPG, PYD terrorist organizations. These aids were given to all of them, and it still continues. They even provide training to them in the region. Now, while these facts stand out, are we still ignoring them?
Just as we have operations against the PKK and its puppies in Northern Iraq, the same situation is much more valid, much more important for Syria. As I always say, one night we suddenly descend on their tops, and we have to.
Aren't we going to make them pay the price of our martyrs? We finished the job of around 30 terrorists in two days.
Together with those in northern Iraq, we have now neutralized over 100 terrorists. This process will continue, we cannot stop. We will root out terrorism and terrorists.”
First of all, everyone has to do their part (talking to the USA about the operation). America has to do its part, too.
If America does not fulfill its duty in the fight against terrorism, what will we do? We'll take care of ourselves. It is not possible to fight against terrorism by obtaining permission from somewhere.”