As the nearly two-month-long conflict in Ukraine rages on, a number of triggers exist that could lead to a nuclear “third world war” in Europe. Nato’s further expansion on the continent, thereby posing a further threat to Russian security, could amount to one such trigger. In fact it is Russian fears about Ukraine’s possible induction into the US-led western security umbrella that led to war in that country in the first place. One will recall Moscow had demanded a written guarantee last December that Ukraine, formerly an entity within the Russian Empire and the Soviet Union thereafter before becoming independent in 1991, will not seek membership of Nato. But the 30-member alliance dismissed its demands and ultimatums, which ended up becoming the spark that lit the fire. Today, however, Nato could conceivably add Finland and Sweden to its club, prospects that are just as worrying for the Kremlin. Finland, which shares a 1,340-kilometre-long border with Russia, will next week explore the option of joining Nato when its parliament receives an intelligence briefing. Prime Minister Sanna Marin says Finland intends to make a decision by mid-summer. Sweden may not advance towards membership at the same pace as Finland, but it appears ready to join the alliance because of the war. Fears about a possible nuclear conflict have been raised across the continent, particularly after recent statements from former Russian president Dmitry Medvedev and US intelligence chief William Burns. “An empty shot in the air” is how Mr Medvedev last week described the news coming out of Finland and Sweden. The Deputy Chairman of the Russian Security Council hinted that, as a result, Moscow will consider deploying nuclear weapons out of Kaliningrad, a Russian exclave in the Baltic region that is sandwiched between Lithuania to its north and Poland to its south but, crucially for Sweden, lies a little more than 500km from its capital Stockholm. Meanwhile, Poland, already a Nato member, is considering allowing the US to deploy nuclear weapons on its soil, prompting a Russian warning that it would respond with like-for-like measures. Mr Burns, meanwhile, warned that a desperate Kremlin might use “tactical nukes” in Ukraine following what he described as military “setbacks” for Russia. “None of us can take lightly the threat posed by a potential resort to tactical nuclear weapons or low-yield nuclear weapons,” the CIA Director said. “Nato would intervene militarily on the ground in Ukraine in the course of this conflict.” He, however, added that the Biden administration cares deeply about “avoiding a third world war – and about avoiding a threshold in which, you know, nuclear conflict becomes possible”. In their statements, spokespersons for the US and Russian governments made clear the diametrical contradiction of their countries’ assessments of the expansion of Nato membership and its consequences. While the Americans see it as fostering peace and stability in Europe, the Russians see it as a provocative and destabilising move. As to why Moscow fears Nato’s expansion more than three decades after the Cold War ended, the answer lies in the events that unfolded after the Soviet Union collapsed. One such development was former president Mikhail Gorbachev’s failure – at least in the eyes of Russia’s elites today – to seek written guarantees from Nato leaders that the alliance will not expand into Eastern Europe by adding countries that were previously in the Soviet orbit, which it did in the intervening years. Mr Gorbachev has in the past insisted that western leaders had assured him of no expansion, but he conceded no written guarantees had been provided. Fast forward to 2022 and Russia, it seems, is seeking to push back against what it views to be an egregious act by the West. With last week’s statement, Mr Medvedev effectively raised the level of the nuclear threat in Europe. Beyond that, he said, Moscow will significantly shore up its territorial and naval forces, as well as air defences, in the Gulf of Finland. He added that there would not be any "nuclear-free status of the Baltic" and that Russia would seek to restore balance by, in his words, rightfully deploying nuclear weapons in the region. While these remarks were directed at Finland and Sweden, the message will have been loud and clear in the three former Soviet republics in the Baltic region – Latvia, Lithuania and Estonia – as well. The situation in Ukraine, meanwhile, is getting more dangerous. It is set to escalate further as more advanced weaponry arrives from the West, which Russia could intercept and destroy. Amid the lack of progress in negotiations between the two countries, and increased Ukrainian military self-confidence, fighting seems to have escalated around Kyiv once again, and not just in the Donbas region in the country’s east, which Moscow has sought to liberate. Amid these developments, it is worth pointing out that the Biden administration is showing little interest in cooling the temperatures with the Kremlin. It continues to mobilise sanctions against Russia and block any support for its leadership anywhere in the world. Determined to exclude Russia from the G20 summit this fall, the administration has put pressure on the host nation Indonesia to disinvite Moscow. Some parties are trying to persuade Washington to make the distinction between excluding Russia and disinviting its leadership from the G20 summit to avoid further antagonising the Russian people. But so far, it is not clear whether US President Joe Biden will accept such a compromise. Mr Biden, who has been gradually ratcheting up tensions with Moscow, has made a number of accusations against Russian President Vladimir Putin, including describing him as a thug. He has also accused the Russian army of genocide inside Ukraine. While he made the statement in personal capacity, the question being asked is whether the President may using the pretext of what he characterises as “genocide” to intervene directly in Ukraine in the future. As the temperatures continue to simmer over the war, it isn’t at all surprising, then, that Europe and the world at large are deeply worried about nuclear escalation.