VIENNA -- US Secretary of State John Kerry blamed Hamas for powering through a ceasefire with Israel, brokered by the Egyptian government and accepted by Israel's cabinet Tuesday morning.At least 35 rockets have been fired from the Gaza Strip since the ceasefire was set to begin, mere hours ago. "I cannot condemn strongly enough the actions of Hamas in so brazenly firing rockets in multiple numbers in the face of a goodwill effort to offer a ceasefire, in which Egypt and Israel worked together, that the international community strongly supports," Kerry told reporters in Vienna on Tuesday morning.Kerry said that Hamas is "purposely playing politics" by continuing the rocket fire, using innocents as "human shields... against the laws of war." "And that is why they are a terrorist organization," Kerry added.The secretary is ready to fly back to the region at any moment, he said, and is declining to do so now in the hopes that Egypt's effort to broker a ceasefire itself will bear fruit. But the US fears the potential for an even greater escalation of violence, he said."Perhaps reason could prevail" within Hamas, Kerry continued, "if the political wing could deal with the military wing."Kerry canceled a trip to the Middle East on Tuesday morning, relying instead on a ceasefire brokered by the Egyptian government between Israel and the Palestinians to at least temporarily end the conflict.Israel's government has accepted the proposal, but Hamas - the primary perpetrator of rocket fire from Gaza against Israeli cities and towns over the last month - has yet to respond to the paper, which calls for an end to hostilities followed by dialogue."The Egyptian proposal for a ceasefire and negotiations provides an opportunity to end the violence and restore calm," Kerry said. "We welcome the Israeli cabinet’s decision to accept it. We urge all other parties to accept the proposal.”Kerry will instead return to Washington from Vienna, where he has been engaging Iranian leadership directly over its controversial nuclear program."Secretary Kerry has been deeply engaged in conversations with Prime Minister Netanyahu, Egyptian government officials and President Abbas throughout this difficult period, and the United States remains committed to working with them and our regional partners to find a resolution to this dangerous and volatile situation," State Department spokeswoman Jen Psaki said.