US President Donald Trump said on Friday that Russia should be allowed back into the G8 group of industrialised nations, which became the G7 when Moscow was suspended in 2014."I have been Russia's worst nightmare ... but with that being said Russia should be in this meeting. Why are we having a meeting without Russia being in the meeting?" Donald Trump said at the White House shortly before departing for the G7 summit, which will take place on Friday and Saturday in a town outside Quebec City, Efe news agency reported."Whether you like it or not, and it may not be politically correct, but we have a world to run" and Russia "should be at the negotiating table," said the President, who since taking office has faced allegations of collusion between his 2016 election campaign and the Russian government.Russia was suspended from the G8 after its 2014 annexation of Crimea, an area with a Russian-majority population that became part of Ukraine in 1954.Trump's attendance at the G-7 gathering comes amid tensions over new steel and aluminum tariffs the US has imposed on some of its closest allies, including the European Union and summit host Canada.In a message earlier Friday on Twitter, Trump said the talks at the summit would "mostly centre on the long time unfair trade practiced against the US".The White House said on Thursday that Trump would cut short his attendance at the summit by a few hours and travel on Saturday to Singapore, where he is scheduled to hold a historic meeting on Tuesday with North Korean leader Kim Jong-un.