Barack Obama has warned of the fragility of American democracy, making reference to the rise of Nazi Germany in the 1930s.
Speaking during a question and answer session at the Economic Club of Chicago on Tuesday, the former US president warned against growing nativism in America.
“We have to tend to this garden of democracy or else things could fall apart quickly,” Mr Obama said.
“That's what happened in Germany in the 1930s which, despite the democracy of the Weimar Republic and centuries of high-level cultural and scientific achievements, Adolph Hitler rose to dominate,” he said, according to newspaper Crain’s Chicago Business.
“Sixty million people died,” he added. “So, you've got to pay attention. And vote.”
Although Mr Obama did not mention Donald Trump by name, some believed his comments were aimed at the current US president and his “Make America Great Again” rhetoric - which critics argue has fuelled nationalism.
Mr Trump has been accused of fuelling anti-Muslim sentiment across the US.
Palestinians burn an Israeli and a U.S. flag during a protest against the U.S. intention to move its embassy to Jerusalem and to recognize the city of Jerusalem as the capital of Israel, in Gaza City 'Day of the Dead' parade, Mexico City A Rohingya woman washes clothes in a stream at Palong Khali refugee camp near Cox's Bazar, Bangladesh An officer carries a school girl away from continuing battles with police and protesters in Kenya Authorities investigate the pickup truck and scene of a terror attack in downtown New York Near the parliament building in Athens, Greece, a girl holds a placard reading, "Where is my mother, where is my father?" Some refugees have announced a hunger strike, as they seek reunification with family members in Germany South African opposition Party Economic Freedom Fighters (EFF) members dance during a demonstration to express their solidarity with the Palestinians in front of the Embassy of Israel in Pretoria. Today is the 100th anniversary of Britain's Balfour Declaration, which helped lead to Israel's creation and the Israel occupation of Palestine The first customer shows his new iPhone X after buying it at an Apple Store in Beijing, China Protesters at a climate demonstration prior to the UN Climate Change Conference COP23 in Bonn, Germany Riot police run past an excavator, during a demonstration against open-cast brown coal mining of Garzweiler, northwest of Cologne, Germany A Houthi follower emerges from a gap in a flag as he attends a rally to show support to the Palestinians in Sanaa, Yemen Russian solider stands in line at a military parade, that marks the anniversary of the 1941 parade, when Soviet soldiers marched towards the front lines of World War Two, at Red Square in Moscow, Russia A woman wearing a scarf to cover her face looks on as she waits for a passenger bus on a smoggy morning in New Delhi, India. Air pollution reached unprecedented levels in the city, prompting the government's Central Pollution Control Board to recommend emergency free public transport Shiite faithful pilgrims gather between the holy shrine of Imam Hussein and the holy shrine of Imam Abbas for Arbaeen Protesters rally near the U.S. Embassy in Manila to protest this weekend's visit of President Donald Trump Polish nationalists light flares as they take part in the March of Independence 2017 in Warsaw Pepole hold placards demanding the return of Lebanese Prime Minister Saad Hariri from Saudi Arabia during the annual Beirut International Marathon Gianluigi Buffon reacts during Italy's World Cup qualification match against Sweden. He retired from international duty after the Azzurri failed to go through. An Iranian boy rides a bicycle through the rubble from damaged buildings in the town of Sarpol-e Zahab. A 7.3-magnitude earthquake left hundreds killed and thousands homeless two days before. Military vehicles and soldiers patrol the streets in Harare, Zimbabwe Donald Trump has awkward water bottle moment at the White House while talking about his latest overseas trip in Asia Riot police use stones to disperse the convoy of Kenyan opposition leader Raila Odinga as they attempt to access the Uhuru Park grounds upon his return Women shout pro-freedom slogans as people carry the remains of Mugees Mir, a suspected militant who according to local media was killed in an encounter with the Indian security forces in Zakura, during his funeral in Srinagar Participants crossing the Jiaozhou Bay Bridge as they compete in the 2017 Qingdao International Marathon on the Sea in Qingdao, in China's eastern Shandong province Israeli security forces carry away an Ultra-Orthodox Jewish demonstrator as they disperse a protest against Israeli army conscription in Bnei Brak, a city near Tel Aviv People and soldiers celebrate after the resignation of Zimbabwe's president, Robert Mugabe Former Bosnian Serb military chief Ratko Mladic shouts at the presiding judge during the verdict hearing in his genocide trial, in The Hague, Netherlands Comrades of missing crew members express their grief after the Argentine Navy announced that the sound detected in the missing submarine search is consistent with an explosion Zimbabwe's former vice president Emmerson Mnangagwa arrives ahead of his inauguration ceremony to be sworn in as president in Harare A Pakistani protester throws a tear gas shell back towards police during a clash in Islamabad Mount Agung volcano is seen spewing smoke and ash in Bali Rohingya refugee Amina Khatun, 55, rests at the bank of the Naf river after crossing it on an improvised raft to reach Bangladesh, in Teknaf. Two of her sons were killed by gun fire when her village was attacked by Myanmar military, she says People fall as police fire tear gas to try control the crowd trying to force their way into Kasarani Stadium to attend the inauguration of President Uhuru Kenyatta in Nairobi South Korea's Hyunmoo II missile is fired during an exercise at an undefined location in the east coast of South Korea An activist pours gasoline as an effigy of President Rodrigo Duterte and U.S. President Donald Trump burns during a protest action against Duterte's plan to set up a Revolutionary Government, along a street in metro Manila, Philippines A nurse takes blood for a HIV test for French President Emmanuel Macron as he visits the Delafontaine Hospital on World Aids Day A man dressed as Santa Claus skiis down a mountain during the Saint Nicholas Day at the Alpine ski resort of Verbier, Switzerland A supporter of Salvador Nasralla, presidential candidate for the Opposition Alliance Against the Dictatorship, puts a balloon on the shield of a soldier in a protest while the country is still mired in chaos over a contested presidential election in Tegucigalpa, Honduras A man exercises in a park on a winter morning in Kolkata, India Former Georgian President, Mikheil Saakashvili, flashes a victory sign after he was freed by his supporters in Kiev
In November, the President came under fire for retweeting inflammatory videos from the Twitter account of a British far-right, ultra-nationalist figure, which contained anti-Muslim content.
His actions were publicly rebuked by prime minister Theresa May, whose official spokesperson condemned the president's actions as "wrong".