Kautilya's Arthashastra 7.7.23

7.7.23

bhūyo vā yācitaḥ svabalarakṣārthaṃ durdharṣam anyadurgam āsāram aṭavīṃ vā paradaṇḍena marditukāmaḥ prakṛṣṭe 'dhvani kāle vā paradaṇḍaṃ kṣayavyayābhyāṃ yoktukāmaḥ paradaṇḍena vā vivṛddhas tam evocchettukāmaḥ paradaṇḍam ādātukāmo vā bhūyo dadyāt //

When, with the desire of putting down a king in troubles due to the diminished strength of the elements of sovereignty, or with the desire of destroying his well-begun work of immense and unfailing profit, or with the intention of striking him in his own place or on the occasion of marching, one, though frequently getting immense (subsidy) from an assailable enemy of equal, inferior, or superior power, sends demands to him again and again, then he may comply with the demands of the former if he is desirous of maintaining his own power by destroying with the army of the former an impregnable fortress of an enemy or a friend of that enemy or laying waste the wild tracts of that enemy, or if he is desirous of exposing the army of the ally to wear and tear even in good roads and good seasons, or if he is desirous of strengthening his own army with that of his ally and thereby putting down the ally or winning over the army of the ally.