When did Pakistan bomb the Chagai mountains?

When did Pakistan bomb the Chagai mountains?

پاکستان نے چاغی کے پہاڑوں پر کب بمباری کی؟
Explanation

Chagai-I is the code name of five simultaneous underground nuclear tests conducted by Pakistan at 15:15 hrs PKT on 28 May 1998.

Test site: Ras Koh Hills, Chagai, Balochistan, Pakistan

Period:   28 May 1998

Number of tests: 5

Test type: Underground tests