The leaders of Canada, Mexico and the United States signed a new North American trade deal Friday. Justin Trudeau, Enrique Pena Nieto and Donald Trump inked the deal in Argentina, ahead of the opening of the G-20 summit. It will, however, take a while for the agreement to take effect as lawmakers from all three countries have to approve the scheme, officially known as the US-Mexico-Canada Agreement, or USMCA. The pact underpins $1.2 billion in annual trade among the three countries. It replaces NAFTA, a pact that Trump had roundly criticized in his 2016 presidential campaign, terming it the worst trade deal in history and blaming NAFTA for the loss of American manufacturing jobs since it went into effect in 1994. Trump called the deal a “model agreement that changes the trade landscape forever” at a news conference with his North American counterparts in Buenos Aires, Argentina, ahead of the G-20 …