Vladimir Putin has warned Nato countries that deploying weapons or soldiers to Ukraine would cross a “red line” for Russia and trigger a strong response, including a potential deployment of Russian missiles targeting Europe. Nato countries have warned Putin against further aggression against Ukraine as foreign ministers gathered in Latvia to discuss the military alliance’s contingencies for a potential Russian invasion. Tensions have soared following a buildup of nearly 100,000 Russian troops, as well as tanks, artillery, and even short-range ballistic missiles, within striking distance of Ukraine’s borders. While a similar crisis played out over a Russian troop buildup in April, officials from the US and Ukraine have warned that the threat of a Russian offensive this winter remains very real because of a failing ceasefire agreement and a worsening political climate. In his most expansive comments on the crisis yet, the Russian president on Tuesday complained of Nato’s historical expansion to Russia’s borders and warned that substantial Nato military support for Ukraine would cross a “red line” for Russia. “You asked about Ukraine, where are these red lines?” he said in televised remarks during an investment conference. “They are above all in the creation of threats to us which could come from [Ukraine].” In particular, he warned against the stationing in Ukraine of missile defence systems similar to those in Romania and Poland. Putin claimed they could serve as cover to deploy offensive weapons such as Tomahawk missiles capable of reaching Moscow in minutes. “We would have to create a similar threat for those who are threatening us,” he said, warning that Russia could deploy hypersonic missiles. “And we can do that already now,” he added. Putin’s remarks seemed designed to echo the fears of Europe’s cold war missile crises. Nato countries such as the United States have supplied Kyiv with military aid, including lethal weapons like Javelin anti-tank missiles. But aside from isolated discussions among lawmakers, there are no plans to station air defence batteries in Ukraine. In Riga, the capital of Latvia, the US secretary of state, Antony Blinken, said on Tuesday that the west was on alert over Russia’s “increasingly bellicose rhetoric” and “unusual” troop movements. “Any escalatory actions by Russia would be a great concern to the United States … and any renewed aggression would trigger serious consequences,” he told reporters ahead of Tuesday’s talks. Western countries have sanctioned Russia for sending its soldiers and heavy weapons to fight in south-east Ukraine, where more than 14,000 people have been killed since 2014. Since 2017, Nato has deployed four international battalion groups to Poland and to the Baltic countries of Estonia, Latvia, and Lithuania, in order to deter Russia from launching an attack. The UK foreign secretary, Liz Truss, met British soldiers stationed in Estonia on Tuesday. She called the country, which borders Russia, the “frontier of freedom”. “Britain stands with our @NATO allies to defend liberty and democracy and counter malign threats,” she wrote in a tweet. Speaking to reporters, she added: “Any action by Russia to undermine the freedom and democracy that our partners enjoy would be a strategic mistake.” Across, the border, Russian officials hurled accusations at Nato countries, saying that they had been forced to send troops to the borders with Ukraine and Belarus because of Nato’s aggressive posture. Sergei Lavrov on Tuesday compared the situation in Ukraine to that of Georgia in 2008, indicating Russia would be ready to launch a larger war over its support of the separatist territories it controls in Ukraine. Fyodor Lukyanov, an expert on Russian foreign policy, wrote last week that Russia was seeking guarantees that Ukraine would never join Nato even in an an unofficial capacity as an ally against Russia. Belarus has also threatened to join Russia if war breaks out with Ukraine. Minsk on Monday announced it would hold joint military exercises with Russia on Belarus’ southern borders. It claimed they were provoked by Ukraine’s deployment of troops to the border area due to the growing migration crisis sparked by the Belarusian leader, Alexander Lukashenko. In remarks on Tuesday, Lukashenko said he was ready for the country to host Russian nuclear missiles if western countries were to do similar. “We are ready for this in Belarus,” he told an interviewer from Russian state television, adding that he believed the infrastructure like silos for holding nuclear weapons was in working order.