The United States currently has close to 44 Ground-Based Interceptors (GBIs) deployed in Alaska and California to defend all of the 320 million Americans living in the United States of America against North Korean nuclear Intercontinental Ballistic Missiles (ICBMs). The last of the 44 GBIs are being deployed and will be completed next month in Ft. Greely, Alaska. There is no system deployed in the world today, with a proven capability, that can shoot down ICBMs other than the United States Ground-Based Midcourse Defense (GMD) system with the 44 GBIs, sensors (in space, on land, and at sea), and its Command and Control, Battle Management, and Communications (C2BMC) at Schriever Air Force Base, Colorado Springs, Colorado.

President Donald Trump stated, in an interview on North Korea with Fox News on October 11, 2017, that there is a 97% reliability and confidence in this system with the GBIs to successfully intercept a North Korean Nuclear ICBM aimed and targeted at the United States of America. (Link to a transcript of the interview)

In his response to a question on North Korea during the interview, President Trump stated “You look around and you see what’s going on. Take a look at what we are buying right now with jetfighters, all of the equipment we are buying. You know it is two things really, it is jobs that is far less important, but we build the greatest military equipment in the world. We have missiles that can knock out a missile in the air 97 percent of the time. If you send two of them, they are going to get knocked down.”

All of the current 44 GBIs are comprised of three different generations, deployed since 2006, have been tested over the past eleven years. A GBI generation is determined by the configuration of the booster vehicle and the Exoathmospheric Kill Vehicle (EKV). (Learn more about the GBI booster configurations and EKVs here.) Below are the three different generations of GBIs currently deployed today.

• “Generation 1” GBIs include the Configuration 1 booster and the Capability Enhancement-1 (CE-1) EKV.
• “Generation 2” GBIs include the configuration 1 booster and the CE-2 EKV.
• “Generation 3” GBIs include the configuration 2 booster and the CE-2 Block 1 EKV.

The GBI program has had 18 intercept tests since 1999 with ten successful intercepts. However, only six of these 18 tests – beginning in 2006 – used one of the three GBI generations that are deployed today. These six intercept tests of the actual three generations that are operationally deployed today have had five successful intercepts. The ten GBI intercept tests prior to 2006, which had five successful intercepts, used older generations of the GBI that are not deployed and were essentially early proof of concept prototypes for the GBI. Based off of lessons learned from these pre-2006 GBI intercept tests, there were substantial upgrades and modernizations made for the currently deployed generations of the GBIs. The six GBI intercept tests that used a version of the three currently deployed generations, are highlighted in yellow in the chart below.

Below is the breakdown of which GBI generation, that are deployed today, used in each of the six tests.

• FTG-02: Generation 1
• FTG-03a: Generation 1
• FTG-05: Generation 1
• FTG-07: Generation 1
• FTG-06B: Generation 2
• FTG-15: Generation 3

The two GBI intercept tests in 2010, FTG-06 and FTG-06a, used development prototypes of the Generation 2 GBIs – that are significantly different from the Generation 2 GBI deployed today – that discovered a design issue with the high frequency sensitivity of vibrations caused by its rocket motors in space within the CE-2 EKV’s Inertial Measurement Unit (IMU), or in other words the EKV’s guidance system, which caused an error and made the EKV to lose where it was located in space and thus miss the intercept. The issues with the CE-2 EKV’s guidance system were resolved with a solution – a cradle – that was tested in the FTG-06b intercept test and is on the Generation 2 GBIs that are deployed today. The newest and latest Generation 3 GBI provided and added more extensive solutions with new rocket engines that reduced the vibrations, which had a successful ICBM intercept test earlier this year (Link).

Based off the six tests of the three Generations of GBIs deployed today that represent the entire fleet of 44 GBIs, an assumption is made by the President of the United States that five out of six times, a currently-deployed GBI will intercept its target. That means that a North Korean Nuclear ICBM would have a one-in-six (16.6%) chance of dodging a single GBI. If the U.S. were to fire two GBIs, the chance of North Korean success decreases to approximately 2.8%. (0.166 x 0.166 = 2.78% chance).  Therefore, the probability of the United States successfully intercepting a North Korean ICBM when firing two of the currently deployed GBIs is just above 97.22%. Firing three or four of the current GBIs at one single North Korean Nuclear ICBM would further increase the probability of interception, as would selectively firing the latter generation configurations. There is no complacency, nor is there any doubt in Congress, the United States Military, and the President’s Administration that a more frequent, a more robust, and more realistic operational testing of these three GBI generations against a North Korean ICBM threat target needs to be at a much more frequent rate in order to further validate the confidence and reliability of the GMD system. Upgrades to GBI generations 1 and 2, by replacing the older Configuration 1 boosters with the new Configuration 2 boosters is being done. The eventual replacement of all three generations with the new modular Redesigned Kill Vehicle (RKV), that is easier to produce, more efficient, offer better communication, and is considerably less expensive is projected to be first deployable in 2021 after a series of tests and will further increase the reliability of the GBIs for capacity increases and a necessary stepping stone to the multi-object kill vehicle (MOKV).