Raytheon is producing additional Standard Missile-6 all up rounds for the U.S. Navy under a $149 million contract modification.

The modification is for 74 of the air defense missiles, together with spares, containers and company services.

"The SM-6 has advanced capabilities and speed," said Mike Campisi, Raytheon's SM-6 senior program director. "Combatant commanders want their deployed ships armed with as many of these interceptors as possible, and we're ramping up production to meet that need."

SM-6 is a surface-to-air supersonic missile that uses both active and semi-active guidance modes and advanced fuzing techniques to destroy incoming aircraft and missiles. It was first deployed by the Navy in 2013, and Raytheon has so far delivered more than 160 of them.

Raytheon said the new order, when combined with the nearly $110 million long-lead material purchase made in March 2015, brings the total value of full-rate production of SM-6 missiles for fiscal year 2015-16 to $259 million.

"Future contract modifications include options which, if exercised, would bring the cumulative value of this contract to nearly $563 million," it said.