President Vladimir Putin said on Thursday that South Korea would be making "a big mistake" if it decides to supply arms to Ukraine and that Moscow would respond to such a move in a way that would be painful for Seoul. Putin, who was speaking at a news conference in Vietnam, was reacting to a report from Yonhap news earlier on Thursday which said South Korea would review the possibility of supplying weapons to Ukraine after Putin and North Korean leader Kim Jong-un signed a mutual defence pact a day earlier. He warned Seoul against moving to supply weapons to...