Nuclear security

Which nations increased the size of their nuclear arsenal in 2017?

The several months have been a busy time for nuclear weapon issues: North Korea conducted its sixth nuclear test, the 2018 Nuclear Posture Review steered U.S. nuclear policy towards a return to great power competition and suggested the development of two new nuclear weapons in addition to other expensive nuclear modernization programs.
But these were not the only events that impacted the global nuclear balance.
A new report from the Stockholm International Peace Research Institute shows that although the U.S. and Russia decreased the number of nuclear warheads in their stockpiles in 2017, smaller nuclear powers like China, India, North Korea and Pakistan took steps to expand their arsenals.
According to the report China increased its total number of warheads by 10, from 270 to 280. India was believed to have between 120 to 130 warheads in 2017, and is estimated to have added 10 more warheads as well, for a 2018 total between 130 and 140. Pakistan also increased its arsenal by 10, bringing their approximate warhead stockpile to between 140 and 150. SIPRI estimates that North Korea has anywhere between 10 and 20 warheads.