So far, the U.S. has largely limited its assistance to the Syrian opposition to funding for communications and other logistical equipment.
The U.S. decision to provide more aid directly to the rebels is designed to increase the pressure on Assad to step down and pave the way for a democratic transition. The aid is also intended to help the Coalition govern newly liberated areas of Syria and blunt the influence of extremists.
"For more than a year, the United States and our partners have called on Assad to heed the voice of the Syrian people and to halt his war machine," Kerry said in Rome. "Instead, what we have seen is his brutality increase."
The Coalition, which has been hampered by the same infighting that has dogged the opposition since the uprising began, has struggled to agree on the leadership of a transitional administration since the opposition umbrella group was formed late last year. The group has met on previous occasions to select an interim prime minister, but has failed to reach a compromise.
In a statement posted on its Facebook page, the group said the March 2 conference in Istanbul was canceled for "logistical reasons." It said it would announce a new date as soon as possible.
Walid al-Bunni, a spokesman for the Coalition, said the meeting was pushed back "for few days" to allow for more consultations with members of the opposition inside Syria who have been hampered by security issues and because some local councils who were supposed to take part in the conference were holding elections.
Associated Press writers Albert Aji in Damascus, Syria, Ryan Lucas in Beirut, and Matthew Lee in Rome contributed to this report.
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