Shiism is very much preferred over Sunnism because, traditionally, Shiism is way too much progressive than Sunnism, which is essentially reactionary. But converting a Sunni into Shia sect is probably harder than making them devout Protestants.
Building mosques and remote-controlling imams in foreign countries is the way Salafi ideology seeks influence in overseas Islamic communities. Turkey does that, too. These radical Sunni countries have strong "Sunni industrial complex" that, as in the case of Turkey, receives much more funding than Ministry of Education.
Governments should never allow that to happen. If an Islamic community need a place of worship, they better build it themselves. If they are devoted enough, they should be able to build on. No need to set up huge complexes.
China's government is right, and should be even more cautious, not to allow Saudi, Turkish or Rome influence in religion. State must control and regulate. Once you let the religion becomes a business and a tool for political power, it becomes dangerous. You cannot reason with a religious nutjob. Better snip them off at the bud.
I am, personally, more at ease with having relationship with enlightened Iran than other Sunni backward ideologies. Hopefully, Iran will progress further and get rid of the clergies' hold on the public policy and foreign diplomacy. I surmise the regime Iran has today is the result of geopolitical context; once it changes, Iran will adopt a more liberationist and progressive domestic policy.
Even before recent Wikileaks exposure of Saudi efforts to spend billions of oil money to fund Salafism and extremest agenda in form of Madrasah/Mosque/Islamic Centers everybody knew what they are doing but since West always had a dual-face standard, the world never had the chance to know the seriousness of these terrorist actions that is blossomed in form of ISIL, Afghanistan, Pakistan, Yemen, Lebanon, Lybiyan Al Qaeda, Nigera's Beaucoup Haram, Soumalian Al Shabab, Russian Chechnian Salafis, Turkey's Salafism, Saudi,s , etc...
This kind of historical behaviour that West has implemented toward world serious issues has encouraged these pest movements to expand as they have enough oil to fund them.
They close their eyes on multi-billion dollars of oil money Saudi and other Gulf states spend to promote Takfiri agenda where ever they could. Funny thing is that no only Western govs but also Western non-profit human right groups are silent when it comes to the harsh treatment of women and foreign workers in Arab countries.
Women are not allowed to drive cars or even sit behind wheels of a turned off car. Women can not go out of home without a Mahram (bother or husband or father, etc). Foreign workers in Arab countries are treated worse than slavery era in USA. You can google Qatari, Saudi or Bahraini human right issues. you never hear a word from Westerners against it nor any actions.
All they do is to impose sanctions against an Iran that women are not allowed to live like humans but also a country that %65 of its higher education graduates are women, a country that promote women to be active in each and every field that men do. A country that women are treated even better than men! They impose sanction on human right basis because they don't like to see drug traffickers who enter tons of drug into country hanged. They don't like Iran to hand murderers or those who used armed protests against Iranian national security. It is all bad for Iran but when USA executes a murderer it is all OK... It is bad for Iran to hang absolute pests but it is always Ok to see Saudis celebrate their 100th be heading by sword. Iran is bad because its women are a big part of its scientists and engineers who work for a better Iran. They impose sanctions on Iran just because it wants to have all the benefits of nuclear technology but cheer Israel for having hundreds of ready to fire NUKES!! They never say a word about Israelis terrorizing Iranian scientists in open day light but are very worried that Iran hangs the terrorists who committed those terrors. They cheer Israel and help em with billion of new weaponry when Israel threatens IRan with a nuclear attack or to attack Iranian nuclear sites, but when Iran helps a Lebanese party that has ministers in government, that has PMs in parliament, that has helped Lebanon from Israeli yearly attacks, Iran is the devil and should be sanctioned!!
The funny thing is that Iran is helping Arabs against an Israeli and Western invasion and occupation, but Arabs themselves are making up with Israelis, promising Israelis that they (Arabs) will join Israel against Iran!!!!
The world is a very funny jungle... It used to be like this and will stay the same...
Everyone knows that %99 of all terrorists are Takfiris who are funded and still get supported by Saudis and their fellas. But instead of trying to drain the source or as you said, just nipping the bud, they fight Iranians and Shias who are fighting this ugly Salafi terrorism.
Shia is welcomed everywhere it went because it not only never Takfirs any other religion or sect but also promotes progress, science, logic and toleration. Saudi and others spend billions through a clear obsession for Iran, they follow Iran in +130 countries to see if anyone's heart is with moderation they kill it and replace it with hate and Takfiri Salafism.
They openly declare their plans to spend tens of billions of dollars every year to make every remaining Muslim a terrorist and hater.
World should wake up now eventhough it is late... but late is better than never... we all must fight this Zomby terrorists or there will come a day that non would be safe from these blood drinker, uneducated, terrorist nutjobs....
All China should do is to let the people live their lives in North Western China but at the same time stop any funds or Takfiri help to reach China....