Nevada: The United States conducted a subcritical nuclear test earlier this week at the Principal Underground Laboratory for Subcritical Experimentation (PULSE) facility in Nevada, according to a statement released by the US Department of Energy's National Nuclear Security Administration (NNSA). This test marks the third of its kind under President Joe Biden's administration. 

The experiment, carried out on Tuesday, is part of the Nimble series and aims to collect "essential data" concerning the safety and effectiveness of the country’s nuclear warheads. Subcritical tests, which involve nuclear materials and possibly high explosives, are designed to avoid creating a critical mass of fissile material, thus ensuring no nuclear yield occurs. These tests are consistent with the United States' interpretation of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which bans nuclear explosions but permits subcritical tests.

The NNSA emphasized that subcritical tests are crucial for maintaining the reliability and safety of the US nuclear arsenal without resorting to nuclear explosive testing. The US has upheld a moratorium on tests involving nuclear explosions since 1992. Despite this, subcritical tests have continued, with the previous one conducted in September 2021. 

"This experiment and all 33 previous US subcritical experiments were consistent with the zero-yield standard of the Comprehensive Nuclear Test Ban Treaty," the NNSA stated. Marvin Adams, Deputy Administrator for Defence Programs, highlighted the importance of these tests, stating, "We plan to increase the frequency of these subcritical experiments so we can continue to gather important data on nuclear weapons materials, with no technical need for a return to underground nuclear explosive testing." 

Global Context: Rising Nuclear Tensions 

The announcement of the subcritical test comes amidst increasing global nuclear tensions. Russian President Vladimir Putin recently ordered his military to practice the deployment of tactical nuclear weapons, citing threats from Western nations, including France, Britain, and the United States.

Russia's defense ministry confirmed that missile forces in the Southern Military District, along with aviation and naval units, will participate in these exercises. The Southern Military District, based in Rostov-on-Don, borders Ukraine and includes areas of Ukraine currently under Russian control. Belarus is also expected to be involved in these drills. The Russian Foreign Ministry linked these exercises to what it described as "militant statements" by Western officials, particularly highlighting remarks from French President Emmanuel Macron and British Foreign Secretary David Cameron. The delivery of US Army Tactical Missile Systems (ATACMS) to Ukraine was also cited as a contributing factor. 

Significance and Implications 

The linkage of routine nuclear exercises to an ongoing conflict, as Russia has done, is highly unusual and has drawn significant attention from global powers. These exercises are expected to involve mock warheads being transported and prepared for deployment, demonstrating the readiness of various delivery systems such as the Iskander, Kinzhal, Kalibr, or Novator 9M729 missiles, as well as air-dropped bombs. 

William Alberque of the International Institute for Strategic Studies noted the strategic importance of these exercises, particularly the interest in the Kalibr Kh-102 missile. "The Kalibr Kh-102 is of great interest because the Kh-101 has been so comparatively easy for Ukraine to shoot down," Alberque said, suggesting that the war in Ukraine has heightened the significance of tactical nuclear weapons for Russia as a means of deterring and potentially countering NATO forces.