Officials are considering possible dates and locations should ongoing talks with Iran and regional mediators progress in the coming days, a CNN source added, describing the discussions as preliminary. "We need to be ready to organize things quickly if the situation moves in that direction," the source said. Saturday’s marathon meeting in Islamabad was the culmination of weeks of negotiations with senior U.S. officials and mediators, including Pakistan as well as Turkey, Egypt, and Oman, among others. A regional source told CNN that another round of talks could follow and that Turkey is working to bridge differences between the two sides. Before all parties agreed on Islamabad, several locations were considered for Saturday’s talks, including Geneva, Vienna, and Istanbul. Geneva and Islamabad are again under consideration as possible options for the next round, a source familiar with the talks said. Administration officials still hope a diplomatic solution is possible, sources familiar with the negotiations said. Depending on the pace of talks in the coming days, the U.S. and Iran could extend the ceasefire deadline to allow more time for an agreement.