US President Barack Obama has invited his Vietnamese counterpart Truong Tan Sang for an official visit to Washington this month, a government official said Thursday. Sang was to travel to the United States on July 24, an official from Vietnam's Ministry of Foreign Affairs said. This is only the second visit by a Vietnamese head of state since the two countries normalized relations in 1995, according to a report of DPA. He will have a meeting with President Obama the next day (July 25).