LONDON – Russian President Vladimir Putin may consider striking British military assets or conducting a nuclear test if Western countries permit Ukraine to use long-range missiles against Russian targets, according to analysts. As tensions between Russia and the West continue to rise over the conflict in Ukraine, British Prime Minister Keir Starmer and U.S. President Joe Biden are meeting in Washington to discuss whether Kyiv should be allowed to deploy U.S. ATACMS or British Storm Shadow missiles in its defense.

Putin issued a stark warning on Thursday, stating that such a decision would fundamentally alter the nature of the conflict and bring the West into direct confrontation with Russia. He promised an "appropriate" response but did not provide details. However, in June, Putin hinted at the possibility of supplying Russia's enemies with weapons to target Western assets abroad or deploying missiles capable of reaching U.S. and European allies.

Analysts have suggested Putin’s options for retaliation could range from escalating conventional warfare to sending a nuclear signal. Ulrich Kuehn, an arms expert from the Institute for Peace Research and Security Policy in Hamburg, said a nuclear test might be one way for Putin to demonstrate intent. “This would be a dramatic escalation,” he said, noting that nuclear testing would be unprecedented since 1990. Kuehn speculated that Putin might resort to such a measure if he feels that his previous red lines have been ignored by the West.

Gerhard Mangott, a security specialist from the University of Innsbruck, shared a similar view, adding that while a nuclear test is possible, it remains unlikely. He suggested Russia could conduct such a test in the east of the country to reinforce its threats. Russia’s U.N. Ambassador Vassily Nebenzia further emphasized the gravity of the situation, warning that NATO’s involvement in allowing long-range strikes would make it a "direct party to hostilities against a nuclear power."

In a more direct threat, Sergei Markov, a former Kremlin adviser, predicted that Russia would consider Britain’s involvement an act of aggression if Storm Shadow missiles are used against Russia. Potential retaliatory actions could include closing embassies, attacking British drones or warplanes near Russian territory, or even targeting F-16 aircraft stationed in Romania or Poland. Markov argued that the West is crossing a critical red line, one that would force Russia to respond with greater intensity.

Despite repeated warnings, Ukrainian President Volodymyr Zelenskiy has urged Western nations to adopt a firmer stance against Moscow, dismissing Russia's threats as attempts to deter necessary military support. Putin’s spokesman, Dmitry Peskov, reiterated the seriousness of the Russian leader’s latest message, describing it as “extremely clear and unambiguous.”

The broader question for the West is where Putin's actual red lines lie. While nuclear strikes are considered extreme, more predictable responses might include stepped-up attacks on Ukrainian civilian infrastructure or hybrid warfare tactics such as sabotage and election interference in Europe or the U.S., according to Kuehn. Mangott predicted that Kyiv could face a heightened military response should long-range missile strikes be approved, but downplayed the likelihood of a direct Russian assault on NATO territory.

As the West continues to weigh its options, Sergei Mironov, a leader of a pro-Kremlin political party, issued a final warning: “The moment of truth has come for the West, whether it desires a full-scale war with Russia.” The potential decision to allow long-range missile use by Ukraine, coupled with the increasing military and strategic assistance provided by the West, now brings the conflict to a more dangerous precipice.