As the world became more dangerous in 2024, the use of its most dangerous weapons has become more likely. This trajectory raises the stakes for the new Trump administration as it tries to end wars in Europe and the Middle East and, more broadly, to reverse the ominous path toward the use and proliferation of nuclear weapons that has been accelerated by these conflicts. Vladimir Putin became more aggressive in Ukraine last year, engineering the collapse of the nuclear guardrails built over seven decades between the U.S. and Russia and lowering the threshold for the use of nuclear weapons. He announced that Russian nuclear forces were on full combat alert and soon followed with military exercises to test the readiness of Russia’s non-strategic nuclear forces in a combat scenario. Putin capped the year by launching Russia’s new hypersonic ballistic missile against targets in Ukraine, while formally announcing a revised Russian nuclear doctrine that officially lowered the threshold for the use of nuclear weapons to meet a conventional threat to Russian territory. The revised doctrine also states that an attack against Russia by a non-nuclear power with the participation or support of a nuclear power will be seen as their joint attack on Russia. U.S. defense analysts assess that Russia is not preparing to use nuclear weapons in Ukraine, and Putin’s nuclear threats are dismissed by Ukraine’s supporters as “bluffs” to curtail support for Ukraine. But Putin’s rhetoric and policy revisions have had a significant effect. Prior to the war in Ukraine, it was extremely rare for American or Russian leaders to imply a threat of nuclear use. Putin’s threats have dramatically shifted the lexicon on nuclear use, lowering the psychological barrier for use and reopening a debate in Ukraine on whether that nation needs a nuclear deterrent. Such rhetoric, combined with the change in strategic doctrine, lowers the threshold for using nuclear weapons not only in the current conflict but in future ones. Furthermore, Putin must recognize that, to maintain deterrence, he cannot keep issuing threats before action is eventually required. Russia’s need for support in the Ukraine war and the consequent 2024 Russia-North Korea mutual defense treaty make it more likely that an unpredictable North Korea will gain more sophisticated nuclear knowledge and technology. Russia also led the effort in the U.N. to ease the pressure on North Korea’s nuclear program by vetoing a resolution that would have extended the mandate of the panel tasked with reporting on North Korea compliance with U.N. sanctions. These developments, on the heels of North Korea’s announcement that it would no longer seek reunification and reconciliation with South Korea, have reopened debates in both South Korea and Japan on whether a non-nuclear status still serves their national security interests. Similarly, the Middle East war has undermined nuclear guardrails. Iran may become a nuclear weapons state in response to Israel’s debilitating attacks on it and its proxies. This, in turn, has unleashed speculation as to whether Israel will preempt such a possibility by escalating the conflict with a direct attack on Iran’s nuclear facilities. Iran’s closer cooperation with Russia and China has also increased concerns about further cooperation on developing Iran’s nuclear capacity. Looming over the deterioration of the nuclear guardrails and contributing to lowering the nuclear threshold is China’s rapid expansion of its nuclear force in 2024. As the Defense Department’s recent report on China’s military capabilities explains, China “probably perceives that a stronger nuclear force is needed to deter U.S. intervention, check potential nuclear escalation or first strike, and will allow for increased control of the scope and scale of escalation during a conflict in a way its previously smaller and less diverse nuclear force could not.” Further raising the nuclear risk levels are advancing technologies. AI can dangerously automate the command and control of nuclear weapons. The increased role of nuclear energy to address climate change could increase the spread of nuclear weapons capability, unless diligently addressed. President-elect Donald Trump has indicated that resolving the wars in Ukraine and the Middle East is a top priority for the incoming administration. But solutions to these conflicts must include reversing the acceleration towards the use and spread of nuclear weapons. Risk reduction measures are a feasible starting point. Russia signaled that it hasn’t totally dismissed the need for these types of measures with its notification in advance to the Pentagon before its November launch of its ballistic missile strike in Ukraine. China and India’s reported roles in signaling Putin to deescalate his nuclear threats indicates their understanding of risk reduction. While the inclusion of nuclear risk reduction measures as part of any agreement to end the conflicts may seem like small steps in the face accelerating threats, the understanding of the risks involved is the bedrock for more far-reaching measures. Dr. Lori Esposito Murray is senior fellow for national security and managing director of CEO programs at the Council on Foreign Relations.