Not paying the loans will cause your servicer to begin reporting late payments, and eventually your loans will go into default. You will still owe the money, but your credit score will be absolutely trashed for around 7 years. A low credit score will make it very difficult for you in the US to refinance loans, buy a car, qualify for an apartment, get a credit card or personal loan, or buy a house.

You could call your servicer and ask about other deferment options, such as in cases of hardship. When you refinance the loans, you could look for some that offer forbearance for foreign grad schools. Idk if they exist but it’s worth a try.

You could take out a grad loan but you might run into the same problem where repayment starts immediately instead of being deferred. You’d have to research your options carefully.

Is this a degree you can get in the US instead? You would be able to defer your loans if it’s a US grad school, right?