Because they give nuclear technology to Iran, flak for North Korea, provide advanced arms to both of those and to Syria, talk the talk but only to pull the wool over our eyes while they back all of our enemies and make as many messes for us as possible. Including recklessly playing with nuclear fire. They are not remotely our friends. And as long as they behave in such ways, we would be entirely right to do everything in our power to tear down everything they touch. We don't because we are saps.
Actually they don't give arms to Korea, well not north Korea. South Korea, however has several divisions of T-80Us facing off with N.Koreas T-62s. As for Iran, that's civilian nuke technology, it's our "ally" Pakistan who keeps giving them Chinese tech (formerly our tech until Clinton came to town) to the Iranians. There was an article posted today again underlying that fact.
Further, they helped us out with Afghanistan by directly arming the Northern Alliance that over threw the Taliban. A lot of those N.Alliance tanks came with slavic crews already inside.
Syria is another matter. That is dumb, plain, dumb, especially when those weapons are just as likely to end up in Chechnya as in Baghdad. They also arm the Israelies and provide Israel with most of its oil.