What if Kido Butai was discovered before reaching Pearl Harbor?

What could Kido Butai do if American surface ships discovered it near Hawaii?

Withdraw and reveal the planned approach, or accelerate and launch an immediate strike at much greater risk.

Discovery close to Hawaii would make the purpose of a six-carrier force difficult to conceal. The stated orders called for withdrawal if the force was found, but the Americans would then know such an approach was possible. An alternative would be to accelerate, launch immediately, and withdraw after the strike. Earlier high-risk proposals contemplated launching all available aircraft and having the crews fly out for recovery by submarines. Those proposals accepted heavy losses to achieve the attack. The hypothetical encounter therefore left Nagumo choosing between abandoning surprise and exposing the force to much greater danger.