Vladimir Putin has said he will consider a military response if Russia feels threatened by Nato, in a sign that he is not ready to de-escalate tensions over a potential invasion of Ukraine. In a combative speech on Tuesday, Putin – who has demanded “security guarantees” from Nato – told his top military commanders that the west was to blame for the rising tensions. It came against a backdrop of a Russian buildup of tanks and artillery for what could constitute an invasion force within weeks. The Russian president has railed against Nato enlargement since the fall of the Soviet Union and accused the west of turning Ukraine against Russia. After a revolution installed a pro-western government in 2014, Moscow annexed Crimea and sparked a conflict in east Ukraine that has left more than 14,000 dead. It has bristled at growing military cooperation between Ukraine and Nato countries. “What the United States is doing in Ukraine is at our doorstep,” he said of Washington’s support for Kyiv. “And they should understand that we have nowhere further to retreat to. Under [US] protection, they are arming and urging on extremists from a neighbouring country at Russia. Against Crimea, for instance. Do they think we’ll just watch idly?” Putin did not specifically refer to the possibility of an offensive operation in Ukraine and Russian diplomats have previously suggested a response could employ other measures, such as moving intermediate-range missiles within striking distance of European targets. That would be a punishment, Moscow claims, for the US’s unilateral withdrawal from a missile treaty in 2018. By massing troops at Ukraine’s borders, however, Russia has made it clear that an attack is on the table. “If our western counterparts continue a clearly aggressive line, we will undertake proportionate military-technical countermeasures and will respond firmly to unfriendly steps,” Putin said in televised remarks. “I’d like to stress that we are fully entitled to do that.” Parts of his speech on Tuesday appeared tailored to give Russia a justification to launch a new military campaign in Ukraine, something it could be ready for as soon as next month. Russia’s defence minister, Sergei Shoigu, said an unnamed private US military company had acquired chemical weapons and was planning to launch a “provocation” in the east Ukrainian cities of Avdiivka and Krasny Liman. Russia’s military previously made similar claims in Syria, although the predicted attacks often did not take place. Putin repeated demands that the west make legal guarantees to ensure Russia’s security, but said he would have difficulty trusting the US to abide by a treaty. “We need long-term legally binding guarantees,” he told military commanders. “You and I know well that even they, legal guarantees, cannot be trusted because the United States easily withdraws from all international agreements it loses interest in for one reason or another … giving no explanations whatsoever.” He pointed specifically to missile defence treaties and the Treaty on Open Skies, which the US left in November 2020. Putin railed at Nato’s expansion and accused western powers of supporting terrorists and separatists in Chechnya, where Moscow fought a brutal series of wars in the 1990s and 2000s. The speech points to a broad reassessment of Russia’s post-Soviet history, in which Putin views Washington and its allies as taking advantage of the country’s weakness. Russia put forward a highly contentious list of security guarantees last week that it says it wants the west to agree to in order to lower tensions in Europe and defuse the crisis over Ukraine, including many elements that have already been ruled out. The demands include a ban on Ukraine entering Nato and a limit to the deployment of troops and weapons to Nato’s eastern flank, in effect returning Nato forces to where they were stationed in 1997, before an eastward expansion. Putin did offer some hope of talks but said Russia needed an immediate answer to its proposals. “There are some signals that our partners are ready to work on this,” he said. “But there’s a danger that they will attempt to stall, dumping our proposals into a swamp, and use this pause to do what they want.” Both Russian and western analysts have said the Kremlin is unlikely to receive the concessions it desires, making a conflict more likely. In that case, Moscow may use the dismissal of its draft treaty as an excuse for launching a military operation in Ukraine. “What’s happening now, this tension in Europe, is their fault,” Putin said. “At every step Russia has been forced to respond, the situation has got worse and worse and worse … And now we’re in a situation where we must make a decision. We can’t allow the situation I’ve described to develop any further.”