China has blown past previous projections for the size of its nuclear arsenal and is now producing even more weapons while expanding its navy, the Pentagon is warning in a new report released Thursday.

The Defense Department specifically believes China had more than 500 nuclear warheads in its arsenal as of May, roughly 100 more than last year, according to its annual China Military Power Report.

DOD also estimates China will likely double that to more than 1,000 nuclear warheads by 2030, and the number is expected to grow, the report says.