Syria's opposition will receive additional assistance if President Bashar al-Assad refuses to attend a peace conference proposed by the US and Russia, US Secretary of State John Kerry said Tuesday.
"If he miscalculates about that as he miscalculated about his own country's future over the course of the last years, it is clear the opposition will be receiving additional support," Kerry said during a visit to Stockholm.
"There will be additional efforts made, and unfortunately the violence will not end," he added.
Kerry did not specify what type of support would be provided, nor from whom.
Washington and Moscow are trying to get Damascus and the rebels to come to the table for talks aimed at ending the armed conflict.
Kerry reiterated that he hoped the peace conference could take place in early June.
"Now President Assad decides," he said.
"We hope we will have a chance to get to that table. If Assad decides not to come, the world will see how empty his rhetoric is, as well as his intent."
More than 80,000 people, almost half of them civilians, have been killed in Syria since March 2011, according to the Syrian Observatory for Human Rights watchdog.