National-security restrictions on exports constrain exporters' market access, but empirical evidence on their domestic costs is limited. We leverage data on export transactions that includes the product classifications used to administer U.S. export controls to document a doubling in the share of U.S. exports subject to controls between 2010 and 2024 and a skewed firm-size distribution among firms that export controlled products. We then exploit the 2014 U.S. restriction on exports to Russia as a natural experiment to examine the impact of export controls on firm-level outcomes. These controls not only reduced U.S. firms' probability of exporting targeted goods to Russia but also had indirect effects: they reduced affected firms' exports of other products and to other destinations and lowered affected firms' average payroll. Our findings imply that the domestic costs of export controls extend beyond direct restrictions.