WASHINGTON – The U.S. Missile Defense Agency awarded Raytheon Missile Systems of Tucson, Arizona a $2.3 billion sole-source contract modification to build as many as 52 Standard Missile (SM)-3 Block 1B interceptors, according to a Dec. 18 announcement from the Pentagon.

In October 2013, the MDA announced its intent to award Raytheon a sole-source contract worth as much as $3 billion for SM-3 Block 1B production. The announcement came shortly after a test that MDA officials described as the Block 1B’s fifth consecutive success.

The Dec. 18 announcement formalized a previous contract action for 44 SM-3 1B interceptors and adds eight missiles with options.

The SM-3 Block 1B, an upgraded version of the Block 1A, was declared operational last year.

A land-based SM-3 Block 1B variant is being developed as part of the MDA’s multiphased plan for defending Europe against missile threats. Installation of the interceptors at a site in Romania is expected to begin next year.

Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.