The labor law in the US is based on hire and fire policies. However, if there is a contract signed between an employer and the employees, the contract controls your employment deals. You can leave the company. But you will have to compensate your employer for whatever the loss your company bears from loosing you. Now, you take the risk. If the employer fires you before the deadline of the contract, it has to pay you all the benefits and the entire salary throughout the contract term. Now you decide, which path to choose.