The UN Security Council met last night to debate Syria, and agreed to push ahead with deploying the full squad of 300 ceasefire monitors called for in Kofi Annan's peace plan. Yet there is patently no ceasefire for them to monitor. Shelling of Homs and other cities has hardly stopped and heavy armour has not been removed from the flashpoints, while the government claims rebels have carried out three major bomb attacks. An editorial in the Washington Post puts it bluntly: Bashar al-Assad's refusal to abide by Annan's plan was a predictable outcome, and one that "has led to the deaths of more than 1,000 people".

But this moment casts light on some interesting questions, and opportunities. If the peace plan doesn't work, is America ready for tougher alternatives? And where does the Syrian opposition go from here?

Plan B?

Yesterday the advance team of 10 monitors visited Homs, and the shelling stopped for the first time since February. Even the mobile phone network came back on. But residents told reporters they had no expectation that the lull would continue.

For now, the countries concerning themselves with Syria have no choice but to pursue the Annan plan for its full 90 days. US secretary of state Hillary Clinton said last week that "despite the evidence thus far" she's still hopeful. But at the Friends of Syria meeting in Paris she also called for "tougher ideas" – and mentioned a few: new sanctions, a UN Security Council-backed arms embargo, and an "assistance hub" for the opposition in Turkey.

Behind this last idea is the somewhat desperate thought that if Syria again threatens Turkish territory – a cross-border shooting incident two weeks ago heightened tension – the country could call on its Nato allies to get involved. Both France and Turkey have proposed a "humanitarian corridor" inside Syria, which would inevitably involve a military mission.

And Susan Rice, the US ambassador to the UN, talked tough after last night's UN debate: "Our patience is exhausted. Let me be plain: no one should assume that the United States will agree to renew this mission at the end of 90 days if there is not a sustained cessation of violence… and rapid meaningful progress on other aspects." She also warned that the US would pursue "other options" before the 90 days were up if the mission "looked like it was not succeeding".

Giving peace another chance

Meanwhile, the opposition has used the partial breathing space of the Annan-fathered "semi-ceasefire" to have a rethink. An intriguing article at Foreignpolicy.com unpicks the divisions among opposition leaders over how far they should support military action against Assad's regime. Events like Rima Dali's solo protest in a Damascus street (here's the video) and the copycat actions that have followed are part of a positive move to re-emphasise a crucial message: that the revolution is for all Syrians, however they choose to combat the regime. That's also reflected by a change of tone in the Syrian Revolution 2011 Facebook page, which has been boosting the Free Syrian Army every Friday – but is now sending a more peaceful, inclusive message.

Further reading: Is the Syrian army falling apart, and what happens now? Renegade general Akil Hashem tells all to Foreign Affairs magazine.