In June of last year, China claimed the number one ranking on the TOP500 list of the fastest supercomputers in the world with the Sunway TaihuLight. It is capable of 93 petaflops, or 93 thousand billion (quadrillion) floating-point operations per second. It replaced Tianhe-2 as the fastest, while at the same time being 3x as fast.
It seems unlikely Sunway TaihuLight will hold its top ranking for long, however, as China plans to achieve a supercomputing milestone before the end of 2017. According to AFP, work is being done on a prototype for a machine capable of performing a billion billion (quintillion) calculations per second, effectively making Sunway TaihuLight look slow. Once working, it will be the first example of an exascale supercomputer.
We shouldn't expect to see a fully-working exascale supercomputer until 2020, though. China carries out development on a Five-Year-Plan period, with the latest spanning 2016 to 2020. Delivery of this new supercomputer in its final form will occur at some point in 2020, when it will be installed at the National University of Defense Technology (NUDT) in Hunan, whose motto is "Excel in Virtue and Knowledge; Strengthen the Armed Forces and the Nation."
A notable feature of the Sunway TaihuLight is a lack of US technology. The supercomputer used chips sourced from within China instead, more specifically, it used the 260-core manycore SW26010 processor designed by the National High Performance Integrated Circuit Design Center in Shanghai. We can probably expect the new exascale supercomputer to make the same claim while cementing China's place at the top of the supercomputing charts.
Meanwhile, according to The Next Platform the US hopes to have an exascale supercomputer by 2021.