Do you think China or Russia would defend Iran and risk their populations with nuclear attack??? I don’t think so so don’t be foolish . If the Americans attack Iran it would only destroy the Iranian nuclear reactors (Given that, Iran has ignored the UN and European Union for nuclear inspections/inspector teams ) not the oil fields where China gets some of their crude from . China also gets crude from Canada and Chinese state companies have been actively investing in Canada energy sector like the Dubai gov’t and its very recent purchase of Pengrowth INCOME TRUST. So you think China will attack Canada given that some of their oil imports come from Canada (like Iran) and with the Tar sands increase oil production (where most of Canadas oil will come from in the next 20 yrs) China increase needs for oil from Canada will increase not decrease in the near future.Even Russia is forcing Iran to accept UN nuclear inspectors . Russia will not back Irans side just like when Isreal attack the nuclear facilities in Iraq. The French and the Russians did nothing. At that time Iraq was the 5th biggest military. UN arms inspector teams after the first gulf war said that after Isreal attack on the Iraqi nuclear reactors in the mid 80’s caused the Sadaam nuclear program to be delayed for 20 yrs .

Now if US attack North Korea ..China will defend North Korea ..China has already declared this and has been China’s intention since the 50’s. Just like if China attacks Taiwan or Japan ..US will defend these two countries also. China knows that.