North Korea's Embassy in Beijing appears to have undergone expansion and renovation work recently amid strengthening ties and growing high-level exchanges between Pyongyang and Beijing, sources said Thursday. The interior expansion work involved two buildings, reportedly including dormitory facilities, with some of the work being detected around the time of leader Kim Jong-un's surprise visit to the Chinese city of Dandong last month, according to sources familiar with the matter. Construction safety netting was seen around buildings inside the embassy compound and near its main gate. The sources also said there were indications that Pyongyang had sought contributions from North Koreans staying in China to help cover the costs. Renovation work at the embassy has often drawn attention as it could be a sign of preparations for Kim's possible trip to Beijing, given that heads of state sometimes visit their country's diplomatic missions during their overseas trips. The renovation work came as North Korea and China have stepped up efforts to strengthen bilateral ties through a series of high-l