Ukraine’s ex-president Petro Poroshenko returned to Kyiv from Europe on Monday despite the risk of arrest, vowing to help protect the ex-Soviet country from a possible Russian invasion. Poroshenko, who served as president from 2014 to 2019, was placed under investigation for high treason and left Ukraine in December. He returned to Kyiv early on Monday on a flight from Warsaw and passed through passport control amid chaotic scenes, saying later that border guards had tried to prevent him from entering the country. A court in Kyiv was to decide later Monday whether to place Poroshenko in pre-trial detention. Thousands of his supporters gathered near the airport to meet Poroshenko. He told them he had returned to help Ukraine face the “growing threat of Russian invasion” and accused his successor, President Volodymyr Zelensky, of “betrayal” of the country. Tensions are at an all-time high between the West and Russia, which Ukraine accuses of having massed troops on its border ahead of a possible attack. On Friday, Washington accused Moscow of sending saboteurs trained in explosives to stage an incident that could be a pretext to invade the pro-Western neighbour. “We are here to unite and defend Ukraine,” Poroshenko told the crowd, which held up posters reading “We Need Democracy” and “Hands off Poroshenko”. “Now I’m heading to the court where we’ll give them a fight,” he said. Poroshenko, 56, is one of the country’s richest men. He was elected president after Russia annexed the peninsula of Crimea and as fighting escalated between Kyiv’s troops and Moscow-backed separatists in the industrial east of the country. In 2019, he was trounced in a presidential election by Zelensky, a comedian with no previous political experience at the time. Poroshenko is now a member of parliament and leader of an opposition party, European Solidarity. Poroshenko is following in the footsteps of Georgia’s former president Mikheil Saakashvili and Russian leader Vladimir Putin’s top critic Alexei Navalny who both returned to their countries in defiance of the authorities and are now in jail. Navalny returned to Russia on the same day a year ago. Authorities say they are investigating dozens of alleged crimes in which Poroshenko might be involved. He is suspected of aiding the self-proclaimed Donetsk and Lugansk People’s Republics in selling around 1.5 billion hryvnia ($54 million) worth of coal to Kyiv between 2014 and 2015. He faces up to 15 years in prison if convicted in the treason case. Poroshenko has denied any wrongdoing and accused Zelensky, 43, of orchestrating the charges in order to deflect attention from his domestic and foreign policy failures. In a video address on Facebook prior to his departure, Poroshenko accused Zelensky of not doing enough to protect Ukraine from Russia and offered his help. “We are ready to help the authorities. We are ready to share our thoughts and advice,” he said, adding that his party would support “all initiatives aimed at strengthening the defence potential of our state and the European direction of our country.”