ISTANBUL - US Secretary of State Hillary Clinton told Western and Arab nations at a meeting in Istanbul on Wednesday that a transition strategy in Syria must include President Bashar al-Assad's full transfer of power, a senior US State Department official said."Tonight the secretary laid out a set of essential elements and principles which we believe should guide that post-Assad transition strategy, including Assad's full transfer of power," the official told reporters after the meeting.The official said Clinton had also decided to send Fred Hof, a senior State Department official who works on Syria, to Moscow on Thursday to hold follow-up conversations with Russia.The official sidestepped a question on whether Russia was willing to increase pressure on Assad to go, saying one reason for sending Hof to Moscow is "to get a sense of how close we are."The official all but acknowledged the failure of UN special envoy Kofi Annan's six-point peace plan."We have all been hoping, expecting, pressuring Assad to live up to his commitment to meet Kofi Annan's six points," the official said."In the absence of any significant movement by Assad on any of the tracks and in fact increased violence, it's time for the international community, working with the Syrian people, to start fleshing out the alternatives to Assad and how this is going to go," the official added.France had also announced at the meeting it would hold a full "Friends of Syria" meeting in Paris on July 6, the US official said.In a written statement, host country Turkey said the members had agreed to convene a "coordination group" to provide support to the Syrian opposition. Each country had agreed to send a representative to Istanbul on June 15-16 to attend the coordination meeting of all the Syrian opposition groups.Clinton also told the meeting that transition in Syria must include a fully representative interim government that would lead to free and fair elections.She was speaking at a high-level meeting on Syria attended by British Foreign Minister William Hague, Turkish Foreign Minister Ahmet Davutoglu as well as other foreign ministers and high-level envoys from 15 countries and the European Union.Speaking on condition of anonymity, the US official suggested that Clinton was trying to lay down a set of minimum benchmarks for how a transition in Syria could unfold in the hopes Russia might back it despite its past support for Assad.