AMMAN, Jordan Secretary of State John Kerry says the United States and its Arab and European allies will step up their support for Syria's opposition to help them "fight for the freedom of their country" if President Bashar Assad's regime doesn't engage in peace talks in good faith.
Kerry says if the world can't find a path toward a negotiated outcome, the result will be more aid to the Syrian rebels.
He spoke ahead of an 11-nation conference in Jordan on Wednesday night.
Kerry and Jordanian Foreign Minister Nasser Judeh both stressed, however, that the goal is to get the Syrian government and opposition into political transition talks.
Diplomats hope they'll begin next month in Geneva.
Also on Wednesday, Kerry said Iranian fighters and Hezbollah are helping perpetuate Assad's "campaign of terror" in Syria.
Meanwhile, inside Syria, the main opposition alliance on Wednesday urged fighters from around the country to reinforce a rebel-held town under attack by President Bashar Assad's troops and their allies from the Lebanese militant Hezbollah group.
With its appeal, the Syrian National Coalition sought to bolster embattled rebel forces in Qusair who for a fourth straight day Wednesday came under fierce assault by government troops. The town, which is near the border with Lebanon, lies at the heart of a government offensive to secure a strategic strip of land running from the capital, Damascus, to the Mediterranean coast and Syria's seaports.
The Iranian-backed Hezbollah group has been fighting alongside Syrian regime forces in the town and surrounding areas in Homs province for weeks.
"Forces from outside Syria" aim to destroy Qusair and rebels should join the fight to "rescue" the town, George Sabra, the acting chief of the Syrian National Coalition, said in a statement. He also urged Lebanese authorities to respect Syria's sovereignty and prevent foreign gunmen from crossing the border to fight in the civil war.
The Coalition has no control over the mosaic of armed rebel groups fighting on the ground inside Syria, and it was unclear what impact, if any, Sabra's appeal would have.