In the mid-2000s, the United States proposed placing a radar in the Czech Republic and interceptors in Poland to defend against long-range missiles from the Middle East. Russia objected strongly.
In September 2009, the Obama administration announced a different design, called the Phased Adaptive Approach, which uses sea-based and later land-based interceptors and a range of sensors. Aegis Ashore sites were later established in Romania and Poland.
The history shows how missile defense decisions involve technology, alliance politics, and relations with Russia.
