Viewpoints: Is it time to intervene in Syria?
The conflict in Syria appeared to escalate dramatically on Wednesday after an explosion at the National Security Bureau in Damascus killed President Bashar al-Assad's brother-in-law, the defence minister, a former defence minister and the National Security Bureau chief.
For months the UN and Arab League's special envoy, Kofi Annan, has tried to persuade the Syrian government and his opponents to implement his internationally-backed six-point peace plan.
Some Gulf Arab states such have called for the rebel Free Syrian Army (FSA) to be given weapons and financial support, while Russia and China remain vehemently opposed to any sanctions or military action.
But with the suspension of the UN observer mission from Syria, and as fighting escalates and begins to envelope the capital, questions about whether, how or when the international community should intervene persist.
Five leading analysts have told the BBC what they think.
Elliott Abrams, senior fellow at the Council for Foreign Relations and former deputy assistant to US President George W Bush
If we are serious about enhancing Syrians' efforts to bring down President Assad's regime, this means arming the rebels, not hiding behind the current and useless talks. The talks are providing our leaders with a ready excuse for inaction, and President Assad with a facade behind which he continues to kill; they provide no protection or hope for the people of Syria. The courage of the Syrians fighting the regime suggests that with our help - arms, ammunition, intelligence, training - they may win.
The rebels' ability to kill top regime officials suggests that regime collapse may not be months away. But as the death toll rises, and if assistance to the rebels does not bring them a quick victory, we must certainly consider direct military action. Assad, in extremis, may soon decide to use his air force or use chemical weapons against the rebels. Will we stand idly by and watch him gas his own population?
We would be faced at such a point with two choices: use force ourselves, or see the Assad regime murder its way to victory. In strategic and humanitarian terms that would be a disaster for us as well as for the people of Syria. A military action on the order of that undertaken by Nato in Libya, with some Arab League help there, would be needed: air power from Nato bases in Turkey, Cyprus, Italy, and on carriers, plus safe zones in Turkey or inside Syria, would lead to a quick end to the war.
Presidents Assad's reliable troops, a small portion of the Syrian army, are already tired and would be overwhelmed; the defections we already see would quickly grow in number if it were clear that we are in earnest. But Syrians may well ask, are we?
Nikolaos van Dam, former Dutch ambassador to Iraq and Egypt and author of The Struggle for Power in Syria
The more atrocities being committed in Syria, the louder the voices become asking for foreign intervention. Recent massacres have sharpened the discussions. But is such terrible bloodshed enough in itself to drastically change the situation where foreign intervention is concerned? I do not think so. It is highly probable that new massacres will take place, and previous ones tend to be transferred to the back of the minds of those watching from abroad. Now the world is suddenly shifting focus on the assassinations of several top ranking key members of the Baath regime, and what people want to see as a "battle for Damascus".
The Western countries that strongly criticise the Russians and Chinese are not too keen on military intervention themselves either. After the failures in Iraq and Afghanistan they are only too aware of the negative implications of yet another huge and seemingly endless military operation. Nevertheless, they feel morally obliged to react and at least "do something". The dynamics of democracy demand that "something must be done", even if the final results of this "something" are almost predictably negative, if not disastrous.
There is not any guarantee that a peaceful solution can be reached through dialogue, but it is at least worth a serious final effort, as there are no clear satisfactory alternatives. Most other scenarios appear to lead to even more bloodshed and civil war. A precondition to any success is ending the violence, from both sides, and, of course, a preparedness to seriously talk.
If President Assad's past is anything to go by, he will this time lose the chance of serious reform and dialogue with the opposition as well, or has already done so. Also the Syrian opposition refuses to negotiate with Mr Assad any longer. Without a peaceful solution Syria is further heading towards a disastrous and long lasting sectarian civil war. Foreign military intervention, sanctions and increased pressure can do little to prevent that.
Deposing the Assad regime by military means does not imply that subsequently a democracy will be installed. Yet another dictatorship seems the more likely, whether it is as the outcome of a civil war, of an Alawite-led internal military coup, or of foreign military intervention. An authoritarian regime willing to drastically reform towards more democratic rule would, however, be an improvement.
Bruce Riedel, senior fellow at the Brookings Institution and former White House adviser
Syria's embattled President Bashar al-Assad is sitting on a powder keg of angry citizens who want his brutal regime to end.
He also sits on the Arab world's most lethal arsenal of weapons of mass destruction, hundreds of chemical warheads and dozens of Scud missiles which can deliver them anywhere in the Levant. Now there are reports that the regime is moving these weapons out of their usual storage facilities for reasons unknown.
Would Bashar use chemical weapons against a Nato military operation like the one that assisted the Libyan opposition? Almost certainly he would. He clearly has few scruples about mass murder and foreign air bases would be a logical target for Scuds. He might also be tempted to use them against Israel.
Would he use them against his own people? This is harder to know. Using them on Syria's Sunni Muslim majority would antagonise the entire world and set Bashar and his cronies up for war crimes trials. It would mean terrible reprisals by Sunnis sooner or later.
The fact of Syria's chemical and missile arsenal is well known to Nato governments. There is no reason it should discourage support for ending the Assad dictatorship. It does argue for caution in how to do so. Any military operation to end the Syrian civil war needs to be prepared to fight in a chemical environment.
Maria Lipman, editor of Pro et Contra at the Carnegie Moscow Center
"A villainous leader brutally killing his adversaries should be stopped." At first sight the moral clarity of this statement cannot be called into doubt.
But on closer inspection, this sounds like an over-simplification. If "humanitarian intervention" implies use of force, then the intervening party assumes the role of god, as it were - as it decides that some people have to die. While sacrificing your own citizens' lives - in case of a war or other emergency - is a leader's legal prerogative, there is no such prerogative outside one's national jurisdiction.
All the lives lost as a result of the villain's deadly operation remain his responsibility, but once foreign forces intervene, they have to share that responsibility, whether they like it or not. The more casualties there are, the more blurred the original good cause.
If the fight is so atrocious that it calls for an outside intervention, it is hardly one between angels and devils. As it undertakes to protect one side against the other, the intervening forces cannot avoid double standards: by emphasising the atrocities committed by the villain's men and playing down those of their adversaries.
If violence is stopped, the intervention may appear justified, but this is usually not the end of the story. The "winners" will likely seek to secure their victory, and the "losers" - to take revenge. Neither is conducive to peaceful development.
This creates a dilemma for the "force for good": to declare its mission accomplished and leave, thus opening the way for renewed atrocities - or to stay at the risk of getting bogged down deeper in a foreign country. The moral urge to intervene is countervailed by the moral responsibility for the consequences. Liberating itself from the villain and overcoming internal differences is a formidable task for a nation, but outside intervention hardly makes it easier.
PJ Crowley, former assistant secretary of state in the Obama administration
The US and its allies have the upper hand politically. Russia, China and Iran continue to defend Bashar al-Assad, but the costs of doing so are on the rise. It will be interesting to see, in light of the latest developments, whether their calculations change.
The Free Syrian Army is not just holding its own, but can now carry the fight to Damascus and to the heart of the regime. As we saw with Libya, over time, the opposition got stronger (admittedly with outside help) and the regime weaker, until it was overwhelmed. That same dynamic is under way in Syria.
President Assad is a dead man walking, without yet knowing when and how he falls. It could still take a while: he may feel he has nothing to lose and double-down yet again. But now is not the time for the United States or the West to shift its existing political and diplomatic approach and directly intervene militarily.
The escalating violence carries long-term costs. It is going to be difficult to put Syria back together again when the conflict finally ends. What the US, Britain and others should do is make clear to Russia and China that they are backing the losing side and have one last chance to be helpful in pushing Bashar al-Assad aside.
Working with the opposition, we should continue to focus less on the tactical battle and more on the strategic outcome - what happens when the shooting stops and what can best help Syria pick up the pieces and move forward.
Sometimes, less is more. We are in a better position to solve the problem when we avoid jumping in the middle and being seen as part of the problem. The best course right now is to be supportive and patient, admittedly not always an American strength.