BUCHAREST The United States will formally declare its European missile defense system operational on Thursday, almost a decade after Washington proposed deploying a base in Europe to defend against Iranian ballistic rockets.
Here is a chronology of the steps toward the shield:
2007: U.S. President George W. Bush formalizes plans to set up a missile defense base in Poland and a radar in the Czech Republic, part of the United States' larger ballistic missile defense system with sites in California and Alaska.
2009: U.S. President Barack Obama cancels Bush's plans, putting forward a sea-based strategy, arguing ships could be deployed more quickly to counter Iranian rockets. Permanent ground bases are foreseen at a later stage.
2010: The United States offers to send missile defense ships to Europe to protect NATO forces against ballistic rockets with a range of up to 3,000 km (1,875 miles). NATO also agrees talks with Russia, which is deeply concerned about the missile defense shield, to calm Moscow's fears the shield could be developed to counter nuclear weapons.
2011: The United States sends USS Monterey to the Mediterranean, the first long-term deployment of a ballistic missile defense ship. The Netherlands says it will upgrade four frigates with early-warning radars as a contribution to the shield. Turkey hosts a land-based U.S. radar.
2012: At NATO's summit in Chicago, the alliance says it can now protect southern Europe from a ballistic missile limited attack. It plans to cover all of Europe, from Greenland to the Azores.
2013: Russia breaks off the missile shield talks with NATO, after failing to win a commitment that Washington would limit the scope of its ballistic missile defense interceptors.
2015: The United States completes construction of its missile defense ground site in Deveselu, Romania.
2016: The United States declares Deveselu operational and is expected hand over command of the Romanian site to the NATO alliance. Construction starts on a second ground site in Poland.
2018: Polish missile defense site is due to be operational.
(Reporting by Robin Emmott; Editing by Richard Balmforth)