Donald Trump Wants Billions for Missile Defense. Is That a Bad Idea? – The National Interest Online

TheWhite Houses fiscal year 2021 budget requestreleased earlier this month asks Congress for $20.3 billion for missile defense and defeat programs. Nearly half of the request($9.2 billion) is for the Missile Defense Agency (MDA). The rest of the money will go toward amix of missile defense programs outside of MDA ($7.9 billion) and left of launch activities that attempt to disrupt or destroy enemy missiles before they can be fired ($3.2 billion). These request figures are more or less in line with requests from the past two years and should not be regarded as amajor increase.

What makes the FY 21 missile defense budget request noteworthy isnt the amount of money being asked for but the priorities it reveals. Namely, the MDA is focused on erasing the distinction between regional and homeland missile defense systems.

This is not anew line of effort. Greater integration among various missile defense systems is alongstanding policy goal that can now be realized thanks to technical improvements. However, if the MDA is successful the United States will have to wrestle with thorny questions about nuclear stability and the future of arms control.

Missile defense systems can be categorized according to which operational role they play. Regional or theater missile defense systems protect military units, installations, and civil infrastructure. The capabilities that the United States has traditionally used for this mission tend to be mobile and very reliable in testing. Homeland missile defense systems protect the continental United States from intercontinentalrange ballistic missiles (ICBMs). Currently there is only one option for homeland defense, the Groundbased Midcourse Defense (GMD) system, which is bothvery expensiveandnotoriously unreliable.

Improvements in interceptor and sensor technology allow for new mission types that have started to blur the lines between this regional vs. homeland distinction. New interceptors can engage awider range of threats than their predecessors. The most notable example of this is the SM3 IIA,the latest generation of the Standard Missile family, that MDA plans to test against an ICBMrange target in 2020.

Advances in sensors (e.g. radars) and the ability to rapidly share data across different systems further erase the regional/homeland distinction by giving interceptors abigger engagement window.

Without the ability to share data, interceptors are limited by the range of their associated sensors. Alongrange interceptor might be able to outfly its associated radar, essentially reducing the effective range of the interceptor to less than the associated sensor. But if adifferent, remote sensor can share its data then an interceptor could make more use of its maximum range. This allows an interceptor to be launched on data provide from aremote source, also known aslaunchonremote or LOR.

Another benefit of improved sensors and data fusion isengageonremote or EOR, which is essentially an improved version of LOR. In EOR, remote sensors provide all necessary data to an interceptor, detecting launch, and tracking the target. The interceptors associated radar does not have to track the threat in an EOR scenario.

Taken together, new interceptors and sensors will allow capabilities previously used only for regional defense to contribute to homeland defense. The MDAs FY 21 budget request calls for the SM3 IIA and THAAD systems to serve as an additional layer for homeland defense in case the GMD misses its mark. If these efforts are successful, the United States would be able to deploy many more interceptors capable of destroying ICBMrange warheads than it currently fields.

This natural evolution of missile defense technology will create some longterm strategic headaches. China and Russia wont view alayered homeland missile shield that has amuch larger inventory of interceptors in avacuum. Taken alongside recent U.S. investments inlowyield nuclear weaponsand conventional hypersonic strike systems that can destroy time sensitive targets (e.g.mobile, second strike nuclear missiles), the FY 21 missile defense budget seems like America rejecting mutual nuclear vulnerability.

This could prompt offensive nuclear buildups to overwhelm athicker U.S. homeland defense or early attacks against U.S. missile defense sensors that also provideearly warning of nuclear strikesagainst the homeland. China and Russia already have astrong incentive to blind U.S. missile defense sensors in aconventional conflict. Stronger integration of regional and homeland missile defense capabilities will reinforce this incentive.Neither nuclear buildups nor blinding strikes are beneficial for Americas longterm interests.

Greater integration of regional and homeland missile defense capabilities will also make it harder for the United States touse missile defense limitations as abargaining chipin arms control negotiations. Any future U.S.-Russia arms control agreement that reduces offensive weapons, regardless of whether New START is extended, is unlikely to succeed unless the United States is willing to put missile defense on the table. Yet deeper integration of capabilities makes it harder to limit any one system without negatively affecting others.

An expansion of defensive capabilities could make it easier for the United States to reduce its offensive nuclear forces in future arms control agreements. Stronger defenses would allow for U.S. offensive reductions without increasing vulnerability or risk. Alower requirement for offensive capabilities would also take some pressure off the U.S. nuclear enterprise, which is being stretched thin by the demands of the modernization program. However, such an outcome seems highly unlikely.

This article by Eric Gomez first appeared at CATO.

Image:Israel's U.S.-backed Arrow-3 ballisticmissileshield is seen during a series of live interception tests over Alaska, U.S., in this handout picture obtained by Reuters on July 28, 2019. Courtesy Israel Ministry ofDefensevia REUTERS