The NEPTUNE Act grants the Secretary of the Navy authority to contract for the construction of up to two new submarine cable laying and repair ships and their associated materials. Any such contract will be subject to the availability of appropriations and will limit the Federal Government's financial liability if the contract is terminated. Additionally, the bill imposes a critical limitation on the retirement of the existing USNS Zeus . It stipulates that the USNS Zeus cannot be retired or prepared for retirement until a "replacement ship," defined as a Navy-maintained USNS vessel with equal or superior capabilities, achieves full operational capability. This provision ensures the continuous maintenance of essential naval assets for undersea telecommunications infrastructure protection.