BEIRUT: Skeptical Syrian opposition leaders agreed Monday to attend an international conference in Rome after first threatening to boycott the session set to be the centerpiece of Secretary of State John Kerry’s first overseas mission in his new job.

The leaders had protested against what they saw as inaction by other nations in the face of brutal violence from Syrian President Bashar Assad’s regime.

The about-face by Ahmad Moaz al-Khatib, leader of the Syrian Opposition Council, came as residents of Damascus and state-run TV reported a huge explosion and a series of smaller blasts in the capital, followed by heavy gunfire.

Activists said five people were killed in the explosion, which the state-run news agency SANA said was a suicide car bombing.

Kerry not only made a public plea at a joint news conference Monday with British Foreign Secretary William Hague, he also called Khatib “to encourage him to come to Rome,” according to a senior U.S. official.

The official, who agreed to speak on condition of anonymity because he was not authorized to speak publicly on the matter, described the conversation as “good” but declined to offer further details.

Khatib’s spokesman Walid al-Bunni said the council had decided to send a delegation to Rome after all.

Bunni told Al-Arabiya TV that the decision was made based on guarantees Khatib was given by western diplomats that the conference would be different and the opposition would receive real commitments this time.

“We will go and we will see if the promises are different this time,” Bunni said.

After speaking with Khatib, Kerry flew to Berlin from London, the initial 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.”

Kerry agreed.

“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,” he said, 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 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, they should “join us” in Rome.

Earlier in the day, Syrian Foreign Minister Walid al-Moallem said Monday the Assad regime was ready to hold talks with opposition leaders, the first time that a high-ranking Syrian official has stated publicly that the government would meet with the opposition. Moallem made his comments after meeting with Russian Foreign Minister Sergey Lavrov in Moscow.

“We are ready for dialogue with all who want dialogue, including those who are carrying arms,” Moallem said.

“We still believe in a peaceful solution to the Syrian problem,” Moallem said, pointing to the creation of a government coalition that would negotiate with both the “external and internal opposition.”

But Moallem did not spell out whether rebels would have to lay down their weapons before negotiations could begin – a crucial sticking point in the past.

The regime’s proposal is unlikely to lead to talks. The rebels battling the Syrian military have vowed to stop at nothing less than Assad’s downfall and are unlikely to agree to sit down with a leader they accuse of mass atrocities.

But nonetheless the timing of the proposal suggests the regime is warming to the idea of a settlement as it struggles to hold territory and claw back ground it has lost to the rebels in the nearly 2-year-old conflict.

In Washington, State Department spokesman Patrick Ventrell said Moallem’s remarks appeared positive but expressed caution about the seriousness of the offer.

“I don’t know their motivations, other than to say they continue to rain down horrific attacks on their own people,” Ventrell told reporters. “So that speaks pretty loudly and clearly.”

If the Assad regime is serious, he said, it should inform the U.N. peace envoy, Lakhdar Brahimi of its readiness for talks, which Ventrell said it hasn’t yet done.

Andrew Tabler, a fellow at the Washington Institute, called the offer “a sign of weakness.”

“I think everybody knows, including Bashar Assad, that they [the regime] can’t hang onto the whole country,” Tabler said.

The U.N. says at least 70,000 people have so far been killed in the civil war, which began as a peaceful uprising against Assad’s regime.