A minute ago
Before the first nuke landed, the S-ranks immediately reacted upon sensing the incoming nuke. Of course, with them all being S-ranks, some even slightly stronger, their reaction was faster than the man-made nuke dropped at the speed of gravity, not that it would make any difference even if it were supersonic.
Waves of vibrant cerulean mana erupted from them simultaneously. The overwhelming pressure released from over five hundred S-ranks instantly pulverized the earth beneath them, creating a massive crater that spread for tens of miles into the surroundings. Their culminated energies created a force field that spread for tens of miles, if not, hundreds of miles without end.