na hy asyānyatamaṁ kiñcid astraṁ praty avakarśanam jahy astra-teja unnaddham astra-jño hy astra-tejasā
Synonyms
na—not; hi—certainly; asya—of it; anyatamam—other; kiñcit—anything; astram—weapon; prati—counter; avakarśanam—reactionary; jahi—get it subsided; astra-tejaḥ—the glare of this weapon; unnaddham—very powerful; astra-jñaḥ—oh the expert in military science; hi—as a matter of fact; astra-tejasā—by the influence of your weapon.
Translation
(The Lord said) Oh Arjuna there is no other weapon except the Brahmastra to counter act the action of a Brahmastra and therefore, as you are well expert in the military science, get the glare of the weapon subsided by the influence of your weapon as a matter of fact.
Purport
For the atomic bombs there is no counter weapon which can neutralise the effects, But by subtle science the action of similar Brahmastra could be counter acted and those who were expert in the military science in those days could also counter act the danger of atomic bomb like Brahmastram. Son of Dronacharya did not know the art of counter acting the weapon and therefore, Arjuna was asked to counter act it by the power of his own weapon.