Keep in mind, banks in China are controlled by Communist China. This is not a banks decision, this was China's decision.

Chinese banks have attracted the ire of Washington, which has accused them of facilitating the Pyongyang regime's nuclear missile programme by providing financial services and laundering North Korean money.

In June, President Donald Trump hardened his administration's approach on the issue, blacklisting a small Chinese bank over dealings with North Korea. Any companies that do business with banks on the US sanctions list face major penalties.

Since China is home to many of the world's largest banks, any such sanctions would have major repercussions for the global financial system.

Until recently, however, many Chinese banks are widely believed to have been taking that risk, opening accounts for North Koreans despite increasing tensions between Pyongyang and Washington.

Neither side is likely to want to risk escalating economic tensions too far however, with trade between the two nations last year totaling $648.2bn, according to US government figures.

http://www.independent.co.uk/news/business/news/china-banks-north-korea-money-stop-taking-us-sanctions-nuclear-weapons-missiles-a7943116.html