The US president was speaking after meeting G7 and NATO leaders to discuss the incident, which hit a grain silo in Przewodow, near Poland’s border with Ukraine. Authorities in Ukraine and Poland said the explosion was caused by a Russian-made missile, but Biden appeared to back down. He said: “There is preliminary information that disputes that. “I don’t want to say this until we fully investigate it, but it’s unlikely on the trajectory lines that it was launched from Russia, but we’ll see.” The missile had sparked alarming debate over NATO’s Article 5, which means an attack on one member country is considered an attack on all member states. A number of NATO countries and allies took to Twitter to express their support for Poland, including British Prime Minister Rishi Sunak, who “reiterated the UK’s solidarity with Poland”. US Pentagon spokesman Brigadier General Patrick Ryder said America “will defend every inch of NATO territory”. Read more: Poland missile strike may be deliberate attempt to test NATO – but overreaction risks dangerous escalation What NATO Articles 4 and 5 say – as Russia blames missile attack on member state However, Polish President Andrzej Duda said his country was “very likely” to invoke Article 4 later today, which allows a member state to raise a security issue and discuss it. Mr Duda said: “We don’t have definitive evidence at the moment as to who launched this missile… it was probably a Russian-made missile, but that is all still under investigation at the moment.” He added: “We are acting very calmly. “What happened was an isolated incident. “There is no indication that there will be a repeat.” Russia has denied any involvement in the Polish missile, saying reports that it was responsible for it are a “deliberate provocation aimed at escalating the situation”. A UN spokesman said avoiding an escalation of war was “absolutely necessary”, adding that a “thorough investigation” should be carried out.