After U.S. withdrawal from the INF Treaty it has become obvious that nearly fifty years old history of nuclear arms control is coming to its end.
The New START treaty is set to expire on February 5, 2021 and there is little doubt that it will be the end of it. It could be extended if both countries agree (they should express their intention to extend the treaty not later than September 2, 2020). Given the current tensions between the two countries, such an extension would be a practical way forward. However even this relatively straightforward step is in doubt. President Trump condemned New START as one of the “bad deals” negotiated under his predecessor (I’m sure that in view of a certain group of US politicians and experts the Treaty is “bad” because it does not contain special limitations for Russian MIRVed and heavy ICBMs). There are also forces in the United States that believe (for different reasons) it is not in the U.S. interests to participate in the START.
There is no need to negotiate the extension as some experts think. The Treaty has been ratified and has an Article XIV according to which it may be extended to the period of no more than five years should the parties agree to such an extension. So, the Treaty’s extension is only a matter of political will of the leaders of the U.S. and Russia. Technically the extension will only require the exchange of diplomatic notes.
If the system of nuclear arms control is fully dismantled the issue of viability of NPT and CTBT arises.
Besides dismantlement of the entire nuclear arms control system may lead to an uncontrolled multilateral arms race involving strategic, intermediate-range and tactical nuclear and non-nuclear offensive and defensive weapons, as well as cyber warfare systems, laser weapons and other arms innovations.
Do the parties to the Treaty have any motivation to preserve the it by means of extension? I think the answer is yes for both Russia and the United States.
Russia seeks to limit Washington’s freedom to ramp up the US strategic arsenal so as not to be dragged into another unrestrained nuclear arms race. If the United States were no longer bound by the terms of START, it would be able to rapidly increase the number of its nuclear warheads installed on deployed ICBMs from the current 400 to 1200 thanks to its existing upload potential. It would also be able to increase the number of warheads on the deployed SLBMs from the current 900 to 1920 (given the terms of New START, each Minuteman III ICBM can be equipped with three warheads, although since June 2014 they have typically only carried one, the U.S. Trident II missile typically carries four or five warheads each, although each missile can be equipped with eight or fourteen warheads depending on its type: W88 or W76). Uploading U.S. Minuteman and Trident missiles to their full capacity would more than double the total number of U.S. strategic nuclear weapons). The Russian Strategic Nuclear Forces would not be able to respond proportionally to such a massive increase in the US strategic offensive capability.
As for the United States, the benefits of preserving START would also be significant. Keeping START alive would enable the United States to have much clearer idea of Russia’s plans in terms of strategic nuclear weapons, which is extremely important to Washington because in 2021 Russia is expected to launch mass production and deliveries to the armed forces of such new strategic offensive weapons as Avangard and Sarmat ICBM, the new Borei-A class nuclear-powered missile submarines and deeply upgraded Tu-160M2 heavy bombers armed with new weapons. These strategic nuclear systems fall under the scope of START and are therefore subject to on-site verification measures by US inspection groups. Additionally, the United States has no plans of deploying any new strategic nuclear systems up to 2026 (when the extension would run out), which makes such an extension an even more attractive proposition for the Pentagon.
Finally, keeping START alive would enable Russia and the United States to demonstrate to international community their commitment to nuclear disarmament in the framework of Article VI of the NPT. This is an important consideration in view of the Tenth Review Conference scheduled for April-May 2020. Neither would a five-year extension pose any risks for Russian or US national security because under Article XIV of START, each party has the right to withdraw at any time should it decides that that extraordinary events related to the subject matter of the Treaty have jeopardized its supreme interests. 
Moreover, for decades, strategic nuclear arms agreements between Moscow and Washington like the latest START have bolstered strategic stability. These agreements have made it possible for the two countries to maintain a stable balance of nuclear forces affordably and receive exhaustive information about the current conditions and future prospects of the modernization of strategic offensive arms. These accomplishments have been made possible by dozens of annual local inspections and exchanges of information and notifications regarding the condition and transporting of nuclear arsenals, the addition or removal of strategic systems, and exchanges of telemetric data from missile launches.
Past experience suggests that a lack of this information inevitably and logically leads countries to overestimate their opponents’ capabilities and, consequently, increase the quality and quantity of their own arsenals at considerable cost. This dynamic can easily lead to a nuclear arms race. If START were allowed to expire in 2021, strategic stability would be in danger.
Granted, if the information exchanges conducted under the treaty ceased, Russia and the U.S. could still obtain some data through other technical means, but satellite-based intelligence platforms would be a totally insufficient source of information by comparison. For instance, it would then become difficult to determine the number of warheads deployed on ICBMs and SLBMs. Moreover, some US politicians and experts believe that security and stability could be achieved by means of non-legally binding transparency and verification procedures. The Russian position od such ideas is clear – Moscow does not need transparency for the sake of transparency and verification for the sake of verification. They should be closely tied to commitments as regards limitations.
What are the main obstacles to an extension of the START treaty?
The ongoing discussions about the Treaty in the Trump administration are fairly negative. There are two prevailing views. One is that current START should be replaced by the new treaty, which is to be signed between United States, Russia and China, and covering all their nuclear systems. The other view is that START in its current form should be abandoned and the new agreement with Russian Federation should be negotiated with Russia to include all new Russian nuclear weapons systems (not just the Avangard hypersonic glider and Sarmat ICBM but also the Burevestnik nuclear-powered cruise missile and even the Kinzhal airlaunched missile and undersea autonomous vehicle Poseidon, which are not even categorized as a strategic weapon’s systems).
Of course, it would be wonderful if other nuclear states adopted the restrictions and subsequently reductions on nuclear weapons after thirty years of such steps being taken overwhelmingly by Russia and the United States. For instance, it’s frequently suggested that the three other signatories of the NPT – the U.K., France and China – be included in the process first, followed by the four nonsignatories; Israel, India, Pakistan and probably North Korea. This would have a positive political impact on the nuclear non-proliferation regime, especially given the fact that the five NPT members are bound by direct obligations on the issue as per Article VI of the Treaty.
But practically limitations, reductions and the dismantlement of such complex, costly weapons of such critical importance for national security never
come about as the result of general good intentions alone. As demonstrated by the fifty years of negotiations and a dozen of serious and politically binding agreements in this sphere between the Soviet Union/Russia and the United States, such steps are only taken on quite pragmatic, material terms.
First, a state adopts these measures if it is guaranteed tangible security improvements, i.e. limitations and reductions of weapons by the other side.
Second, such steps are possible if the states’ nuclear forces are approximately equal: not because such parity is required for deterrence, but because it makes the parties equally interested reaching an agreement and provides the starting point for it. In this case both parties will have to adhere to the same numerical ceilings.
Third, no one will just trust their opponent’s word on such issues, which calls for an adequate verification system, whose capacities in many ways determine the limits of possible agreements. 
As for an inclusion in a new treaty on limitation of strategic nuclear weapons of any other systems not covered by the present START Treaty, for some of them it is quite possible, for some – difficult but still possible, for some – not possible. Moreover, United States is not the only side which may wish to cover additional weapons systems by the provisions of the treaty, Russia also has its own concerns.
Before starting to consider such a possibility it should be mentioned that normally only comparable types of weapons systems are subject to agreements: if an agreement covers a particular type of weapon by one side, it must include the same system of the other. However, if the parties’ nuclear forces are asymmetric, agreements often provide for a trade-off in which some weapons systems are limited on one side in exchange for different systems on the other.
So, the subject of mutual concerns are hypersonic gliders, long-range air, ground and sea-launched cruise missiles (ALCM, GLCM, SLCM), undersea autonomous vehicles, space-based strike systems, anti-satellite weapons, ballistic anti-missile defense and non-strategic nuclear weapons and cyber weapons.
Some of them like Avangard hypersonic glider can be easily counted against the ceilings of a new treaty since it is supposed to serve as a warhead for Sarmat ICBM. It is also not difficult to limit long-range ALCMs by returning to the old counting rules and airfield inspections. In the past ALCMs were counted under warheads ceilings (START I, II). GLCMs, including Russia’s Burevestnik intercontinental nuclear missile, are even easier to numerically limit in a future agreement through the verification measures provided by the 1987 INF Treaty. SLCMs present a much more serious challenge due to the mobility of their delivery vehicles and universality of their launchers. But technically these difficulties are solvable if there is a political will.
The subject of space-based strike weapons and anti-satellite weapons is more complicated since they have never been subject for any restrictive measures or limitations. But again, if there is a political will, at least as a first step some confidence-building mechanism could be worked out.
Russian Poseidon undersea autonomous systems can not be limited unilaterally and should be subject for a trade-off with the United States.
The issue of agreeing and verifying prohibitions on cyber warfare systems seem irresolvable at this time. First of all one of the main difficulties is impossibility to determine the source of a possible cyber attack – state agency or non-state actor. As for the state – the most that can be hoped for just now is a purposeful dialogue between United States and Russia on a mutual commitment not to launch cyberattacks on each other’s strategic information and command and control systems.
Anyhow, I’m sure that both United States and Russia should explore the possibility of a new bilateral, legally-binding and comprehensive arms control agreement that would succeed START, whether it ends in 2021 or 2026. By its own terms or in conjunction with separate, less formal arrangements, such an agreement would need to address concerns of one side or the other about missile defenses, conventional strike systems, non-strategic nuclear weapons, offensive cyber and space capabilities, and any innovative weapons systems.
Meanwhile, today maintaining stability and predictability is the first order of business for arms control. And to achieve this goal we need to do everything possible to extend START, resume regular talks on strategic stability, abandon launch-onwarning nuclear strategies – this important step would help lower the risk of catastrophic errors. Lengthening the time required for leaders to decide whether to launch a retaliatory strike would not undermine deterrence, since such a second strike would still be guaranteed to inflict unacceptable losses on an attacker and therefore dissuade the other party to strike first.
 Victor Esin “Critical factors for the New START extension”, presented at the meeting of the US-Russian Dialogue on Nuclear issues, Moscow, November 7, 2019.
 Alexey Arbatov “A New Era of Arms Control: Myths, Realities and Options”, Carnegie Moscow Center, October 24, 2019.
Source: RIR Center