The United States and Germany are the main opponents of Ukraine joining NATO too soon, diplomatic sources within the alliance said on Monday, ahead of a 75th anniversary summit of the alliance. A source referred to the US and Germany’s “strong opposition” towards inviting Ukraine to join the alliance without fulfilling the necessary preconditions. “In the end, it will be a decision by the allies to invite Ukraine to join NATO,” the source said. The comments deal a further blow to Ukraine’s hopes of progress, following their anger at a lack of invitation at the last NATO summit in the Lithuania…