President Barack Obama told Americans nervous about terror and the changing economy that the US remains the most powerful nation on the earth and they should not fear the future, in a farewell State of the Union address that drew sharp contrast with Republicans. In an election-year marquee event, Obama hailed a period of "extraordinary change" laden with both opportunity and the risk of wider inequality. A confident Obama sought to cast himself as an optimistic foil to foes who warn the country is going in the wrong direction after his seven years in office. "The United States of America is the most powerful nation on Earth. Period. It's not even close," Obama said in his speech. Obama hailed the "US troops as the finest fighting force in the history of the world." "No nation dares to attack us or our allies because they know that's the path to ruin. Surveys show our standing around the world is higher than when I was elected to this office, and when it comes to every important international issue, people of the world do not look to Beijing or Moscow to lead—they call us," Obama said. While vowing to work to find a cure for cancer, accelerate the shift away from "dirty energy" and end the last remnants of the Cold War by engaging with Cuba, Obama said "America has been through big changes before." "Each time, there have been those who told us to fear the future; who claimed we could slam the brakes on change, promising to restore past glory if we just got some group or idea that was threatening America under control. And each time, we overcame those fears." With less than three weeks until the Iowa caucuses — the first votes cast in the process to replace him, Obama berated talking points used by Republican candidates, saying "anyone claiming that America's economy is in decline is peddling fiction. He also lashed out at rhetoric over the rise of the Islamic State group, which he admitted poses an "enormous danger." "Over-the-top claims that this is World War-III just play into their hands," he said. "Masses of fighters on the back of pickup trucks and twisted souls plotting in apartments or garages pose an enormous danger to civilians and must be stopped. But they do not threaten our national existence," Obama said. "That's the story ISIL wants to tell; that's the kind of propaganda they use to recruit. We don't need to build them up to show that we're serious, nor do we need to push away vital allies in this fight by echoing the lie that ISIL is representative of one of the world's largest religions," he said, referring to Islamic State by an acronym.