Beyond START - Brookings Institution

how many warheads are on its ICBMs and SLBMs,just as only Russia knows the number on its strategicballistic missiles. SORT by itself offers no way for theRussians to confirm the number of warheads on anyU.S. missile, nor for American inspectors to confirmthe number of warheads on any Russian missile.Given that the sides will want confidence in theirability to monitor the other’s compliance with warheadlimits, U.S. and Russian negotiators will mostlikely need START-type counting rules for the follow-ontreaty. Each type of SNDV should be attributedwith a specific number of warheads for countingpurposes. The sides might agree, for example, toattribute each Trident II with five warheads (see thedownloading discussion below), relying on STARTverification procedures to allow Russian inspectors toconfirm that Trident II missiles are deployed with nomore than that number. While there may be some interestin counting actual warhead loads (which couldvary from missile to missile), it is difficult to see howsuch a counting rule could be monitored without extremelyintrusive verification measures.DownloadingRelated to the counting rule issue will be the questionof downloading, that is, removing warheads frommissiles and perhaps removing missiles from missilecarryingsubmarines. In order to maintain a survivableforce, both the United States and Russia will want tospread out their warheads. Neither, for example, willwant to deploy too many warheads on one missilecarryingsubmarine. This is the nuclear stability versionof not putting too many eggs in one basket.The problem is most evident with regard to theTrident submarine fleet. Under START countingrules, 336 Trident II missiles (attributed with eightwarheads each) on 14 Trident submarines by themselvescount as 2688 warheads—well above the 2200limit below which Presidents Obama and Medvedevhave pledged to reduce. For operational and stabilitypurposes, the U.S. Navy may not wish to reducethe number of ballistic missile-carrying submarinesbelow 14. Hence the U.S. need for downloading asreductions are implemented.START allows for downloading missiles by type andattributing a lower number of warheads to those missiles,albeit under a complex set of limitations. Forexample, some Minuteman III ICBMs are alreadycounted as having been downloaded and carryinga single warhead, and some Trident II SLBMs havebeen downloaded as well. 16 START’s verificationrules allow Russian inspectors to spot-check missilesand confirm that they carry no more than the declarednumber of warheads.The negotiators should adopt provisions to permitdownloading ICBMs and SLBMs in the START follow-ontreaty. The negotiators might agree, for example,that Trident II missiles could be downloaded andcounted with five warheads each. START verificationmeasures would permit Russian inspectors to spotcheckindividual Trident II missiles and confirm theycarry no more than the agreed number of warheads.(Similar procedures could be applied to downloadedRussian ballistic missiles.) Even at five warheads perTrident II, however, the 14 Trident submarines carryingSLBMs would be counted as carrying 1760warheads. 17If the START follow-on treaty limits each side to nomore than 1500 warheads, U.S. negotiators shouldseek provisions to allow downloading U.S. and Russianmissile-carrying submarines. For example, eachTrident submarine could be counted as carrying nomore than 12 Trident II missiles (instead of its capacityof 24). Relatively simple monitoring provisionscould allow Russian inspectors to spot-checkthis: Russian inspectors visiting a Trident base couldchoose a submarine at random and ask that 12 missiletubes be opened to confirm that they were empty.(The “empty” tubes likely would contain some ballast,but that would be clearly distinguishable froma missile.) Counting each Trident II as carrying fivewarheads and each Trident submarine as carrying 12Trident II missiles would mean the 14 submarineswould be attributed with 840 warheads.Whatever the particular numbers, downloading willbe a key element for the United States in a STARTfollow-on agreement if that agreement is to limit eachside to a number of warheads less than 2200. TheFo r e i g n P o l i c y at Bro o k i n g s 11