Tucked inside the U.S. Army's Redstone Arsenal in Huntsville, Alabama, Raytheon is assembling missiles destined for U.S. and Japanese warships in the Pacific.

Recently, CNBC was granted exclusive access to the operation, as part of a multi-city, multi-month tour of Raytheon's extensive missile defense operations, including access to classified factories.

Raytheon is currently cranking out about 20 of these Standard Missile (SM) variants per month, comprising a key part of the Lockheed Martin-made Aegis Ballistic Missile Defense System. The SM-6s and longer-range SM-3s missiles are intended to help defend against the increasing possibility of North Korean ballistic missile attack.

Soon, the facility will start producing a next-generation version of the SM-3, called Block II-A, capable of traveling even farther and higher to better intercept an intermediate-range ballistic missile.

Raytheon won't begin delivering Block II-As to the U.S. and Japanese until sometime next year, but already more orders may be coming.

Just this week, congressional defense committees authorized a $700 billion defense spending plan for fiscal 2018. While the National Defense Authorization Act (NDAA) still needs to be passed by both houses of Congress and then signed into law by the president, the legislation incorporated a bigger budget for missile defense – including the White House's last-minute request to add $4 billion for "urgent missile defeat and defense enhancements to counter the threat of North Korea."

That funding will go toward expansions of both the U.S. homeland and various regional ballistic missile defense systems. That will increase spending for programs by Boeing, Lockheed Martin, Orbital ATK, and Raytheon, according to Washington-based Cowen and Co. defense analyst, Roman Schweizer.