In March 1995, McDonnell Douglas was awarded a $99.4 million U.S. Navy contract for engineering and manufacturing development on the Standoff Land Attack Missile Expanded Response (SLAM ER) program. A 13-missile flight test program began in March 1997 following a successful first flight on March 18. Low-rate initial production of 60 missiles began in April 1997, with production expected to continue to 2004. Some 600 SLAM missiles now in the U.S. Navy arsenal will be retrofitted with the SLAM ER upgrade.