The renewal of a three-decade old pact between the United States and Singapore that grants US forces access to the Lion City’s naval and air bases signals that Washington views the city state as a vital part of its Asia strategy for a long time to come, analysts have said.One maritime observer said the renewal of the 1990 agreement – which was all but a formality – was likely to be viewed by China with some trepidation, as it comes amid US efforts to enhance its forward presence in the Asia…