New applications such as remote surgery and connected cars, which are being touted as use cases for 5G and beyond, are mission-critical. As such, communications infrastructure needs to support and enforce stringent and guaranteed levels of service before such applications can take off. However, from an operator’s perspective, it can be difficult to provide uniformly high levels of service over long durations or large regions. As network conditions change over time, or when a mobile end point goes to regions with poor coverage, it may be difficult for the operator to support previously agreed upon service agreements that are too stringent. Second, from a consumer’s perspective, purchasing a stringent service level agreement with an operator can also be expensive. Finally, failures in mission critical applications can lead to disasters, so infrastructure should support assignment of liabilities when a guaranteed service level is reneged upon – this is a difficult problem because both the operator and the customer have an incentive to lay the blame on each other to avoid liabilities of poor service. To address the above problems, we propose AJIT, an architecture that allows creating fine-grained short-term contracts between operator and consumer. AJIT uses smart contracts to allow dynamically changing service levels so that more expensive and stringent levels of service need only be requested by a customer for short durations when the application needs it, and operator agrees to the SLA only when the infrastructure is able to support the demand. Second, AJIT uses trusted enclaves to do the accounting of packet deliveries such that neither the customer requesting guaranteed service levels for mission-critical applications, nor the operator providing the infrastructure support, can cheat.