In the context of the USA: The hypothetical where a geopolitical rival has the capacity to shut down shipping across the entirety of the Atlantic and the Pacif

In the context of the USA: The hypothetical where a geopolitical rival has the capacity to shut down shipping across the entirety of the Atlantic and the Pacific isn't something that will enter the realm of plausibility within the next 5 years or so. 5 years is plenty of time to spin up farms. That's also ignoring the fact that whether we'd even need to spin up farms in a world without subsidies is an open question.