best plan; best policy
Refers to the most effective or wisest course of action in a given situation. Often used in formal or strategic contexts.
今は動かずに待つのが上策だ。
The best plan now is to wait without acting.
正直に話すことが上策
He thought that speaking honestly was the best policy.
Compound of 上 (じょう, 'upper, best') and 策 (さく, 'plan, policy'). The exact historical derivation is uncertain, but the meaning follows directly from the kanji.