When President Hosni Mubarak was overthrown in February, the rejoicing in Egypt was tempered by trepidation elsewhere about the possible implications for regional security. For the best part of 30 years, Mr Mubarak had been seen, in Israel as in Egypt, as the guarantor of the 1979 treaty. Without him, that certainty was gone.

Recent events have shown that such fears were not idle scaremongering. The attacks – claimed by a Palestinian group close to Hamas – that killed eight Israelis in the south of the country last week may be isolated incidents. On the other hand, they strongly suggest that security in the Negev is not what it was.

The sequence of events is confused. Under pressure from Cairo, Israel expressed regret for the death of five Egyptian police. But Israel's response to breaches of its security is always to hit back hard, which risks inflaming existing tensions further. Violence has flared up on the Gaza border, with new Israeli air-strikes and Palestinian rocket attacks; anti-Israel protests have taken place in Cairo.

With the situation in Syria unstable, a new theatre of insecurity in the region is the last development anyone – including Egypt's present military leaders – needs.