Russian, US, Chinese hypersonic arms lack treaty curbs

Significance Russia and China have several hypersonic weapons in service or near readiness. This class of weapon is raising concerns in the conventional and strategic realms, where security tensions are already high. A Chinese weapon tested this year created new concerns by reportedly spending time in near-earth orbit. Impacts Governments will review the survivability of their nuclear forces as a hypersonic arms race develops. The reported Chinese test of an orbital system will increased US call to bring hypersonic technologies into arms control discussions. Chinese advances will spur Washington and some of its regional allies to develop defensive and offensive options to counter such systems.

Current Nuclear Strategies and Arsenals of the United States of America and the Russian Federation

The article holistically analyses current strategies for the use and development of nuclear forces of the USA and Russia and analytically reflects their mutual doctrinal interactions. It deals with the conditions under which the U.S. and Russia may opt for using their nuclear weapons and reflects also related issues of modernization and development of their actual nuclear forces. The author argues that both superpowers did not manage to abandon the Cold War logic or avoid erroneous, distorted or exaggerated assumptions about the intentions of the other side. The text concludes with a summary of possible changes and adaptations of the American nuclear strategy under the Biden administration as part of the assumed strategy update expected for 2022.

ENHANCING EUROPEAN SECURITY: MODERN CHALLENGES POSED BY NUCLEAR WEAPONS

The proposal of Europeanising French deterrence was revived by French President Emmanuel Macron, who declared in February 2020 that French nuclear forces reinforce European security simply by existing and suggested a strategic dialogue with all EU partners regarding the role of French nuclear weapons in European security. Macron further reasoned that this issue is increasingly urgent nowadays as the EU must jointly realise that, because of the lack of a legal structure, they may easily find themselves vulnerable to the resumption of a traditional, even nuclear, arms race on their land. The prospects of global control of weapons and disarmament efforts are very blurry in the times of rising political tensions, revived nuclear arms races, and weakening trust in multilateralism. Nevertheless, this all leads to the necessity to support active actions towards nuclear risk reductions, whichhave recently appeared in some of the multilateral forums. The elimination of nuclear risk is nothing but an intermediate measure to reduce nuclear proliferation dangers until they are liquidated. It is essential to review the risks of accidents involving nuclear weapons and their influence on European security, along with focusing on the role of European nuclear weapon states (NWS), their place in global security and possible scenarios for their future: the authors considered the possible prospects of the EU as another entity with nuclear weapons, as well as the likelihood of the EU as another regional nuclear-free zone and discussed whether the real change is possible.

Nuclear warfare beyond counterforce

A counterforce attack intends to disable an opponent's nuclear arsenal to limit potential damage from that adversary. We postulate a future when hardening and deeply burying fixed sites, transition to mobile strategic systems, and improved defences make executing a counterforce strategy against an adversary's nuclear forces extremely difficult. Additionally, our postulated future has multiple nations possessing nuclear weapons. Consequently, each country needs to consider multiple actors when addressing the question of how to deter a potential adversary's nuclear attack. We examine six nuclear targeting alternatives and consider how to deter them. These strategies include nuclear demonstration, conventional military targets, and attacks consisting of communications/electronics, economic, infrastructure, and population centers that a nation might consider striking with nuclear weapons. Since these alternative strikes require only a few nuclear weapons, executing one of them would not significantly shift the balance of nuclear forces. The attacking country's remaining nuclear forces may inhibit the attacked country or its allies from responding. How can nations deter these limited nuclear attacks? Potentially, threatening economic counter-strikes seems to be the best alternative. How might escalation be controlled in the event of a limited attack? Other instruments of power, such as political or economic, might be employed to bolster deterrence against these types of nuclear strikes.

Mass measurements of 99–101In challenge ab initio nuclear theory of the nuclide 100Sn

The tin isotope 100Sn is of singular interest for nuclear structure due to its closed-shell proton and neutron configurations. It is also the heaviest nucleus comprising protons and neutrons in equal numbers—a feature that enhances the contribution of the short-range proton–neutron pairing interaction and strongly influences its decay via the weak interaction. Decay studies in the region of 100Sn have attempted to prove its doubly magic character1 but few have studied it from an ab initio theoretical perspective2,3, and none of these has addressed the odd-proton neighbours, which are inherently more difficult to describe but crucial for a complete test of nuclear forces. Here we present direct mass measurements of the exotic odd-proton nuclide 100In, the beta-decay daughter of 100Sn, and of 99In, with one proton less than 100Sn. We use advanced mass spectrometry techniques to measure 99In, which is produced at a rate of only a few ions per second, and to resolve the ground and isomeric states in 101In. The experimental results are compared with ab initio many-body calculations. The 100-fold improvement in precision of the 100In mass value highlights a discrepancy in the atomic-mass values of 100Sn deduced from recent beta-decay results4,5.

Mechanosensitivity of nucleocytoplasmic transport

Mechanical force controls fundamental cellular processes in health and disease, and increasing evidence shows that the nucleus both experiences and senses applied forces. Here we show that nuclear forces differentially control both passive and facilitated nucleocytoplasmic transport, setting the rules for the mechanosensitivity of shuttling proteins. We demonstrate that nuclear force increases permeability across nuclear pore complexes, with a dependence on molecular weight that is stronger for passive than facilitated diffusion. Due to this differential effect, force leads to the translocation into or out of the nucleus of cargoes within a given range of molecular weight and affinity for nuclear transport receptors. Further, we show that the mechanosensitivity of several transcriptional regulators can be both explained by this mechanism, and engineered exogenously by introducing appropriate nuclear localization signals. Our work sets a novel framework to understand mechanically induced signalling, with potential general applicability across signalling pathways and pathophysiological scenarios.

Nuclear Physics and Astrophysics Constraints on the High Density Matter Equation of State

(1) This review has been written in memory of Steven Moszkowski who unexpectedly passed away in December 2020. It has been inspired by our many years of discussions. Steven’s enthusiasm, drive and determination to understand atomic nuclei in simple terms of basic laws of physics was infectious. He sought the fundamental origin of nuclear forces in free space, and their saturation and modification in nuclear medium. His untimely departure left our job unfinished but his legacy lives on. (2) Focusing on the nuclear force acting in nuclear matter of astrophysical interest and its equation of state (EoS), we take several typical snapshots of evolution of the theory of nuclear forces. We start from original ideas in the 1930s moving through to its overwhelming diversity today. The development is supported by modern observational and terrestrial data and their inference in the multimessenger era, as well as by novel mathematical techniques and computer power. (3) We find that, despite the admirable effort both in theory and measurement, we are facing multiple models dependent on a large number of variable correlated parameters which cannot be constrained by data, which are not yet accurate, nor sensitive enough, to identify the theory closest to reality. The role of microphysics in the theories is severely limited or neglected, mostly deemed to be too difficult to tackle. (4) Taking the EoS of high-density matter as an example, we propose to develop models, based, as much as currently possible, on the microphysics of the nuclear force, with a minimal set of parameters, chosen under clear physical guidance. Still somewhat phenomenological, such models could pave the way to realistic predictions, not tracing the measurement, but leading it.

O NOVO EQUILÍBRIO REAGAN-GORBACHEV

O texto analisa o encontro entre o presidente estadunidense Ronald Reagan e o primeiro-ministro soviético Mikhail Gorbachev, em Washington, em 08 de dezembro de 1987, para assinar um tratado de diminuição das armas nucleares, que fora firmado em Genebra, em 24 de novembro de 1987, o Tratado de Forças Nucleares de Alcance Intermediário, conhecido como Tratado INF (de Intermediate-Range Nuclear Forces), promovendo uma distensão entre as duas grandes potências da Guerra Fria. Tal evento é analisado em comparação com os objetivos pacifistas da ONU e a política de equilíbrio de poder entre os Estados, a partir do que Norberto Bobbio questiona os rumos do sistema internacional no final dos anos 1980.

Suspension of the Intermediate-Range Nuclear Forces Treaty prior to its withdrawal: the content of custom

The United States suspended the Intermediate-Range Nuclear Forces Treaty (INF Treaty) ‘in accordance with customary international law’. However, State practice prior to the International Law Commission's codification of the law of treaties did not contribute to clarifying the extent of a right to suspend and the proper conditions for its exercise under customary international law. The few instances regarding suspension due to a serious breach did not demonstrate how the treaties in question were suspended but were a mere reference to a right of suspension in diplomatic or political documents. Against that backdrop, this article seeks to delineate what customary rules the United States believed it was observing and to clarify to what extent those rules are identical to or different from the codified rules on suspension in the Vienna Convention on the Law of Treaties (Convention). Because the codified procedural safeguards or the mechanism of acquiescence under Article 65 of the Convention were considered as the progressive development of international law, it appears possible to suspend the INF Treaty unilaterally outside the Convention and under the customary rules by which the United States is bound. The INF Treaty was suspended by the United States and by Russia in sequence. That Russian suspension appears to have been an exceptio non adimpleti contractus to prevent the asymmetric execution of the INF Treaty that had been previously suspended by the United States.