Russian decisions influence China due to them being SCO allies. If Russia decides it is time for something, China would either have to support it or then find itself in a tight situation. That's what I'm saying, it all depends on China's attitude over an hypothetical situation of Al-Assad being taken down by its opposition not named ISIS. China doesn't want a war, because it'd ruin the way it is growing. However, if the situation for it to take sides is forced, who do you think they'd side with? It's no US for certain.
Besides, we're in 21s century, maybe the world is looking for peaceful outcomes instead of war.
PS: and it still depends whether Russia would do all of this because of Syria too.
The issue with selling weapons to Syria, is that protests occurred all over the world because of that. China kept doing it. Now, the relationship between Syria and China is mostly economic, yes, but the issue is how the SCO allies' thoughts and acts are regarding this. And I don't think China would want to end relationship with them over this issue, and they'd be forced to do it based on what the hypothetical situation I have described above.
Under the international law, yes. However, it was the first movement of China like that, and US "retaliated" days after. And China didn't like it one bit.
You can't know the other intents and this might simply heat up a relationship that's already a problem. I'm not saying it matters a lot, but it's a lot suspicious to have said moves being taken for no reason at all.
Is that the perception that you have in Brazil? Because the SCO is not a military alliance. Compared to NATO, its institutional structure is very weak. Right now, they're dedicated to be non-aligned, non-confrontation, and are focusing on security and development in Central Asia, with stability in Afghanistan and Central Asian economic integration as top priorities. Besides, they're looking for expansion into Pakistan and India, and I really don't think that's the smartest move if they want to be turning the SCO into an alliance because there's no way that China, Russia, Pakistan, India and all the smaller countries have enough common ground for an alliance.
China and I guess Russia's interest in Syria with respect to the SCO is to protect the SCO from encroaching terrorism. I don't think we have reason to read into it any further than that. ISIS has already fomented terrorism in Central Asia, where there are many SCO members, and perhaps will invade those countries once they gain the ability to. It's safe to say that everybody's primary goal is defeating ISIS, and this is increasing the probability that long-time rivals like the US and Iran might actually cooperate militarily for once.
And no regarding Chinese warships in Alaskan waters, I gave you the reasons. Militaries do what militaries do. Gathering information, training, etc. I mean, every country understands that every other countries' military does those things. I cannot stress enough how the media blows up every occurrence and makes it look like a big deal because they simply aren't. The Chinese-US relationship simply is not at a tipping point, and neither would China or the US go to war with each other over Syria. Anything else is just paranoia.