Clinton, who is on a tour of South East Asia, spoke to many world leaders over the phone in an effort to de-escalate tensions in Gaza as soon as possible.
"In all these conversations, the Secretary underscored Israel's right to self-defence when rockets are falling on its citizens, and the urgent need for all leaders with influence to use it to seek an immediate de-escalation of tensions," State Department spokesperson Victoria Nuland said.
Clinton has spoken to Egyptian Prime Minister Hesham Kandil, following his trip to Gaza, to UN Secretary General Ban Ki-moon and French Foreign Minister Laurent Fabius, ahead of their trips to the region.
She also called Qatari Prime Minister and Foreign Minister Hamad Bin Jassim Al Thani and Turkish Foreign Minister Ahmet Davotoglu, who have also been active diplomatically.
According to a senior State Department official, Clinton in these calls has been delivering the message that the US is focused on trying to de-escalate the situation, but equally focused on the fact that it is just simply unacceptable for Hamas and its allies to continue firing rockets into Israel, including into the Tel Aviv and Jerusalem areas.
She has emphasised that this has to stop immediately, and that a sustainable and endurable outcome can only come about if Hamas stops using Gaza to threaten and attack Israeli towns, cities and villages.
"So she is carrying that message to her counterparts in the hope that they will use their leverage and influence with Hamas to get them to cease their attacks and then to bring about a de-escalation where we can get to the end of the violence," the official said.
Responding to a question, the US official said Egypt has an important leadership role to play in this.
"It has the relationships in Gaza; Prime Minister Qandil travelled there yesterday and had the opportunity to meet with Haniyeh, and other leaders in Hamas. So we believe that they have the stature, the credibility, and the relationships to be able to persuade Hamas and its allies to stop," the official said.
"So our message to them has been: Use it. Use those things. We recognise that they can't simply snap their fingers, that this is a back and forth, it's a process. There are other actors involved like the Turks and the Qataris and others who also have a role to play. But Egypt's role is absolutely pivotal," the official added.
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