Sudan's financial sector is isolated, given US sanctions and general underdevelopment. It was therefore relatively insulated from the global credit squeeze, but it has home-grown problems, chiefly high levels of non-performing loans (NPLs), which stood at 20% of total loans at end-2009. In 2011-12 the Bank of Sudan (the central bank) will seek to improve banking supervision, restructure the banking system and increase provisioning levels in an attempt to address NPLs. It manages monetary policy largely by issuing Islamic financial certificates, setting reserve requirements and manipulating the exchange rate. After a period of supporting liquidity by making deposits at commercial banks, the central bank is now adopting an austere monetary policy, with higher reserve requirements (which rose from 8% to 11% in 2010), to tackle inflation. Southern Sudan will remain vulnerable to the north's monetary policy and money supply until it can launch its own currency, expected no earlier than 2012.