1. Introduction. International stability and human security in 2018

This is the 50th edition of the SIPRI Yearbook. Over the years it has reflected changes in world politics and military technologies, while consistently providing essential data on armaments, disarmament and international security.

The trends revealed in recent yearbooks have been broadly negative. While there were some positive signs in 2018—notably in detente on the Korean Peninsula, United States diplomacy with North Korea (and a vague road map for moving forward on denuclearization), a concerted effort to address, limit and end the violence in Yemen, the Eritrea–Ethiopia peace accord, and evidence that the United Nations Security Council is starting to address the security implications of climate change—there were also significant negatives. Among these were the US withdrawal from the Iran nuclear deal and the Intermediate-range Nuclear Forces Treaty (INF Treaty), and the persistence of geopolitical tensions in a number of locations. More generally, military spending, arms transfers and the incidence of armed conflict worldwide all remained high. Overall, the balance of negatives and positives remains deficient.

Both the USA and Russia are on a path of strategic nuclear renewal. In the USA, this includes enhanced and modernized nuclear weapons, a proposed new Space Force and an expanded programme of ballistic missile defence. In Russia, the strategic path is no less expansive. Moreover, the use of chemical weapons in Syria in 2018 and an attempted assassination in the United Kingdom using a nerve agent raised further questions about the viability and reliability of disarmament and arms control regimes in the current international political climate.

In the absence of a strongly status quo power, there is less clarity about whether the explicit laws and rules of the inter-national system will be respected, let alone its unstated norms and assumptions. China, Russia and the USA are all actively challenging components of the global order, from the political geography of key regions to the balance of power in international finance. The drift into global instability was demonstrated in 2018 by continuing tensions between the West and Russia, a US–China ‘trade war’ and the power struggle between Iran and Saudi Arabia, pitching them on opposite sides of the armed conflicts in Iraq, Syria and Yemen. 

The intersecting challenges of climate change and insecurity have potentially profound and unavoidable consequences for human security, national security in many countries and international stability. Without corrective action to mitigate carbon emissions and adapt to the con-sequences of climate change, serious difficulties will emerge mid century or before. Some progress is being made in adapting agendas and institutions to face these challenges but, as in arms control and disarmament, the role of cooperation and multilateral approaches remains essential. There is a pressing need to find a way out of the multiple power competitions that characterize world politics.