President George W. Bush and South Korean President Lee Myung-bak opened two days of talks on Friday that are focused on North Korea's unfulfilled pledge to disclose its nuclear activities and a US free-trade deal with South Korea that faces an uphill battle for acceptance by the US Congress. Bush hopes to strengthen sometimes-shaky US-South Korea ties under Lee, who took office in late February and made the United States his first overseas trip. Their meeting took on renewed importance when South Korea announced Friday that it would lift its ban on US beef imports. On North Korea, Bush is embracing Lee's get-tough rhetoric against its communist neighbor. The talks among North Korea and China, Japan, Russia, South Korea and the United States are at an impasse over how the North should make good on its pledge to declare its nuclear and proliferation activities. The two leaders were to have talks Friday night and then more meetings on Saturday along with a brief press conference. They are expected to herald the beef deal, the culmination of lengthy negotiations.