China is in the midst of a “significant” expansion of its nuclear capabilities and may have as many intercontinental ballistic missiles as the United States or Russia by 2030, according to a new global analysis of nuclear weapons.

Beijing is both growing and modernizing its nuclear arsenal, according to an annual report released Sunday by the Stockholm International Peace Research Institute (SIPRI), a group that tracks global security and arms control. China’s military stockpile grew from 410 nuclear warheads last year to 500 as of January, the report found.