Updated 10:30 p.m. ET
BERLIN Skeptical Syrian opposition leaders agreed Monday to attend an international conference in Rome after first threatening to boycott the session that was to be the centerpiece of Secretary of State John Kerry's his first overseas mission in his new job.
Opposition leaders had protested what they see as inaction by other nations in the face of violence from Syrian President Bashar Assad's regime.
Around the time the decision to attend was announced, explosions rocked Damascus, the Syrian capital, residents and state-run TV said.
The blasts followed by heavy gunfire caused panic in the capital, where a massive car bombing on Thursday near the ruling Baath party headquarters killed at least 53 people.
It was not immediately clear what the target of Monday's explosion was and whether there were casualties.
State-run TV reported a "terrorist" explosion at the entrance to the northeastern neighborhood of Qaboun.
Earlier, Sec. Kerry not only made a public plea to the Syrian opposition at a joint news conference Monday with British Foreign Secretary William Hague, he also called Moaz Khatib, leader of the Syrian Opposition Council, "to encourage him to come to Rome," a senior U.S. official said. The official, who spoke on condition of anonymity because he wasn't authorized to speak publicly on the matter, described the conversation as "good" but declined to offer more detail.
Spokesman Walid al-Bunni said the council had decided to send a delegation to Rome after all. Vice President Biden spoke to al-Khatib on the phone Thursday night to welcome him.
Al-Bunni told Al-Arabiya TV the decision was made based on guarantees al-Khatib heard from western diplomats that the conference would be different and that the opposition would receive real commitments this time. "We will go and we will see if the promises are different this time," he said.
After speaking with Khatib, Kerry flew to Berlin from London, the first stop of his first trip as secretary of state - a hectic nine-country dash through Europe and the Middle East.
Kerry had also dispatched his top Syrian envoy to Cairo in hopes of convincing opposition leaders that their participation is critical to addressing questions from potential donors and securing additional aid from the United States and Europe.
"We are determined that the Syrian opposition is not going to be dangling in the wind, wondering where the support is, if it is coming," Kerry told reporters in London after meeting British Prime Minister David Cameron and Hague. "We are not going to let the Syrian opposition not have its ability to have its voice properly heard in this process."
For his part, Hague said the violence in Syria, especially recent scud missile attacks on the city of Aleppo, was unacceptable and that the west's current position could not be sustained while an "appalling injustice" is being done to Syrian citizens.
"In the face of such murder and threat of instability, our policy cannot stay static as the weeks go by," Hague told reporters, standing beside Kerry. "We must significantly increase support for the Syrian opposition. We are preparing to do just that."
"We are not coming to Rome simply to talk, we are coming to Rome to talk about next steps," Kerry said, adding that he was sympathetic to opposition complaints that they were not getting the support they need to defend themselves against the Assad regime or oust him from power.
"I am very sensitive to that frustration," recalling that as a U.S. senator he was one of several who pushed the administration to consider military aid to the Syrian opposition.
"But I am the new secretary of state ... and the president of the United States has sent me here and sent me to this series of meetings and in Rome because he is concerned about the course of events.
"This moment is ripe for us to be considering what more we can do," he said, adding that if the opposition wants results, "join us" in Rome.