The Fortress of Ticonderoga in Upstate New York: it no longer contributes to national security. Source: Vintage Views of New York.
During the Cold War the United States developed a suite of export control and visa requirements to limit the spread of sensitive technologies to hostile powers.
But, the National Research Council says, that was then and this is now: Beyond "Fortress America" National Security Controls on Science and Technology in a Globalized World. It's time for reform. You can read the report online; here are key extracts from the executive summary: