President Park Geun-hye says cooperation between South Korea and the United Statesis key when it comes to preventing North Korea from making a catastrophic miscalculation.Speaking with a delegation of U.S. lawmakers on a four-day trip to Seoul Park said "the surest way to prevent North Korea from making any misjudgment is close coordination between South Korea and the U.S."The head of the U.S. legislative group Congressman Howard "Buck" McKeon said the "U.S. Congress will continue to make an investment in the alliance" and that one of his greatest worries remains North Korea.Late this week North Korea said Pyongyang will take countermeasures against the upcoming South Korea-U.S. joint military drills set to start on August 18.