Islamist terrorism has been the dog that has not barked throughout these astonishing few months of uprisings across the Arab world. Did that change with Thursday's bomb attack in Marrakech?
The blowing-up of a café in Djemaa el-Fna square, which killed 16 people, including 11 foreign nationals, certainly looks like an al-Qa'ida-style attack. There are echoes of the 2003 suicide bombings in Casablanca, also aimed at foreign civilians, which killed 45.
Morocco has not been at the forefront of the Arab Spring, but it has experienced its share of popular protests against a repressive regime. In response, King Mohammed VI announced last month that he would give up some powers and make the judiciary independent. A new constitution is due to be unveiled in June. But there were fresh protests last week rejecting the draft of that constitution.
A security crackdown is now likely. The question is whether the king will use this as an excuse to reverse the reforms, or even to crush the peaceful opposition. This tactic has been attempted elsewhere. In the early days of the Libyan uprising, the Gaddafi regime tried to represent the regime's opponents as terrorists. That failed when the international media were able to expose the lie by making contact with the opposition. But if Islamists do interject themselves into the Arab Spring, it will give repressive regimes a further excuse to clamp down viciously on the mainstream opposition. And Western nations would be more likely to look the other away.
That would be a grave mistake. The protesters across the Arab world have been predominantly secular and peaceful. Their demands for greater freedom are wholly legitimate. The liberty of the Arab world – from Morocco to Syria – is in the West's real strategic interest and the best guarantee of regional stability in the medium term. If the Islamist dog does begin to bark, the outside world needs to keep a sense of proportion and to maintain its focus on the main prize.