loka-vyatikaram ca tam
matam ca vasudevasya
praja—the people in general; upadravam—disturbance; alaksya—having seen it; loka—the planets; vyatikaram—destruction; ca—also; tam—that; matam ca—and the opinion; vasudevasya—of Vasudeva, Sri Krsna; sanjahara—retracted; arjunah—Arjuna; dvayam—both the weapons.
Thus seeing the disturbance of the general populace and the imminent destruction of the planets, Arjuna at once retracted both brahmastra weapons, as Lord Sri Krsna desired.
The theory that the modern atomic bomb explosions can annihilate the world is childish imagination. First of all, the atomic energy is not powerful enough to destroy the world. And secondly, ultimately it all rests on the supreme will of the Supreme Lord because without His will or sanction nothing can be built up or destroyed. It is foolish also to think that natural laws are ultimately powerful. Material nature's law works under the direction of the Lord, as confirmed in the Bhagavad-gita. The Lord says there that natural laws work under His supervision. The world can be destroyed only by the will of the Lord and not by the whims of tiny politicians. Lord Sri Krsna desired that the weapons released by both Drauni and Arjuna be withdrawn, and it was carried out by Arjuna at once. Similarly, there are many agents of the all-powerful Lord, and by His will only can one execute what He desires.
Link to this page: https://prabhupadabooks.com/sb/1/7/32