Speeding the Execution of Arms Deliveries for Allies and Securing Trust Act or the STEADFAST Act This bill addresses issues related to foreign military sales, including by establishing deadlines for responses to certain requests. Specifically, the bill requires responses to requests within a certain number of days, with different deadlines for different types of requests. For example, if an eligible foreign purchaser submits a letter of request for pricing and availability data, the Department of Defense (DOD) must ensure that the relevant agency responds within 45 days of receipt. If a defense industry provider applies for a license to release sensitive technology as part of foreign military sales negotiations, the Department of State must issue a decision within 120 days of receiving the completed application. DOD must modify the foreign military sales process to prioritize certain countries (e.g., Israel, Japan, and NATO members) for rapid technology release review and rapid acquisition of U.S. defense articles and services. Furthermore, the bill increases the value thresholds that a contract must exceed before that contract is subject certain contracts to congressional oversight. (Congress may block a proposed transaction for defense articles or services if the contract's value is above certain thresholds.) The bill also establishes the position of Assistant Secretary of Defense for Technology Cooperation and Security Review. The bill expands eligibility for certain assistance under the Defense Production Act of 1950 to include activities performed in any country, whereas currently the activities must be performed in the United States or Canada.