Last Thursday, there were 16 bomb blasts in Baghdad (72 people killed, 217 injured). On Friday, two big car bombs in Damascus killed 40 people and injured 150. Even for Iraq, where there are suicide bombs every week, that is impressive. For Syria, these were the first terrorist attacks after eight months of non-violent protests. In both cases, however, perfectly sane people suspect that the government itself was behind the attacks.
Iraq's Vice-President Tariq al-Hashemi accused Prime Minister Nouri al-Maliki of planning the attacks. "This style of terrorist attack, it's well beyond even al-Qaeda to do it," he said. "Those who were behind all these explosions and incidents [were] part of the [government] security forces. I'm sure about that."
Vice-President Hashemi was speaking from the semi-independent Iraqi region of Kurdistan, where he fled last week after Prime Minister Maliki accused him of plotting terrorist attacks. The Kurds will protect him because they have rejected Maliki's authority over them, but also because they are mostly Sunni Muslims, like the Sunni Arabs whom Hashemi represents - while Maliki, like most Arabic-speakers in Iraq, is Shia.
Meanwhile, just across the border in Syria, the non-violent revolt against the dictatorship of Bashar al-Assad has turned nasty. Or at least that's what Assad's regime wants people to believe: "We said it from the beginning, didn't we?" said Deputy Foreign Minister Faysal Mekdad, standing by one of the blast craters. "This is terrorism. They are killing the army and ordinary people."
The regime claims that it was al-Qaeda that did the Damascus attacks, with Israeli and American backing - and that all opposition to the Syrian regime is actually terrorism.
However, the leaders of the Syrian democratic movement think that the Assad regime probably organised the attacks itself, to support its claim that there is no non-violent insurgency in Syria, just attacks by "armed terrorist groups".
The response of the United Nations Security Council to these events was telling. It strongly condemned the Damascus bombs and sent its condolences to the victims, their families and the Syrian people - but it did not send condolences to the Syrian government, which would be its usual practice in such a case. Nobody believes Assad's story.
What worries Arabs even more is the sectarian subtext to this story. Assad in Syria, like Maliki in Iraq, is a Shia, while the opposition in both countries is mostly Sunni. The difference is that Assad leads a largely Shia regime that is drawn from the Alawite minority, barely 10 per cent of the population, in a country where most people are Sunni Muslims. Maliki, by contrast, leads a Shia regime in a country that is 60 per cent Shia.
This tells us how likely it is that the regime in question ordered the bombings itself. Iraqi Shias have been under attack by Sunni fanatics for years, but Maliki is in no danger of losing power. He doesn't need to persuade Iraqi Shias that some of their Sunni fellow citizens hate them; they already know that. So why would he attack his own government?
By contrast, Assad faces the imminent risk of being driven from power. He is in the last ditch, and his only hope is to convince the disbelieving world that the brave Syrians who face his tanks unarmed are actually al-Qaeda terrorists. He (or somebody in his employ) probably did order the bombings.
Behind all this looms a larger question: in the midst of liberating itself from tyrannies, is the Arab world about to stumble into a Sunni-Shia religious war? The rhetoric is getting paranoid on both sides, even though the original reasons for these sectarian rivalries in Iraq and Syria have nothing to do with religion.
Iraq's army, and therefore its politics, were dominated by the local Sunni minority because the country was ruled for 300 years by the Ottoman (Turkish) empire, whose state religion was Sunni Islam. Sunni rule was only finally overthrown by the American invasion of 2003, and the wounds on both sides of the religious divide are still raw.
Syria is ruled by a Shia minority only because the French colonial army recruited its local troops from the Alawites, precisely because they were a poor and despised minority. That way, the French reckoned, they would be loyal to France, not to Syria. But domination of the military ultimately let Alawites seize political control in independent Syria.
There is no Shia plot against the Sunni Arab world, just old history that won't go away. The danger is that Arab rulers start thinking that citizens cannot be loyal to the state unless they have exactly the same religious beliefs as their rulers.
The European wars of religion - a century of slaughter - were not really about doctrinal quarrels. They happened mainly because rulers became convinced that they could not be safe if some of their citizens belonged to a different sect. Most countries in the world today are living proof that that is nonsense, but Arab rulers, both Sunni and Shia, are fast falling into the delusion that it is true. That would be a disaster.