Hamas will retaliate. The only thing the Israelis don't yet know is when

"If it doesn't happen today, it will happen tomorrow," the Israeli policeman said. I could hardly disagree. The Eged buses were driving through Jerusalem empty yesterday and the Israeli soldiers above the Damascus gate were crawling beneath bus shelters to examine paper bags.

When Hamas talks about revenge, it usually means what it says.

But I couldn't help asking the policeman why – if retaliation was such a certainty – the Israelis had murdered the Hamas men earlier in the week? He shrugged. "It is a war and we know what war is. You don't need to worry. This is safer than London."

But it's not. Only a day earlier, a bus driver called Menashe Nuriel, en route from Jerusalem to Kiryat Shmona, stopped to pick up a 17-year-old Palestinian who was carrying a bomb. He thought the youth looked suspicious, noticed wires coming from a bag in his hand and wrestled him off the bus while the 46 passengers looked on in astonishment. The bag contained three 81mm mortar shells and explosives and could have killed every passenger aboard. According to Mr Nuriel, the youth "seemed a little weird ... stoned".

Will the next bomber to stop a bus find a driver as smart as Mr Nuriel? That, of course, was the police officer's point as cops and border police lounged in their dozens outside the walls of Jerusalem's Old City.

A few Palestinian boys cursed them – 16 youths were arrested – but if the Israeli police presence had not been so massive, the Palestinian crowds would assuredly have been smaller. Blue and green uniforms attract anger and scorn in equal measure.

So do the press. A Palestinian baker walked up to me, hurled his entire tray of rolls onto the road and then threw the tray at me. "You people live off our suffering," he screamed. "Fuck your sister!"

There were, it's true, a few mild signs that the Palestinian Authority is trying to prevent more bloodshed. Tanzim militiamen are on the streets of Beit Jala each evening to stop freelance Palestinian gunmen firing at the settlement of Gilo – built on Beit Jala's land – and thus prevent Israel's usual revenge: tank fire into the Palestinian village. Palestinian newspapers are also urging an end to suicide attacks inside Israel. The Palestinian news agency Wafa – whose rhetoric is as awful as it was during the 1982 Israeli siege of Beirut – has run an editorial calling for an end to military aspects of the intifada.

In one paragraph, the agency declared: "We have to admit that no matter how many casualties we may cause the Israelis, we will not be able to win the war against them, and threatening the Europeans and the US is a foolish step that will affect us negatively."

Although they may be wise words, they will not be heeded. A hundred thousand Palestinians turned up for the funerals in Nablus this week, mourning two children killed during the attack on Hamas. They had no doubts about what they wanted: retaliation.

Telling the Palestinians to throw shoes and stones rather than bombs at the Israelis – as Wafa advised – is unlikely to cut much ice. Like the cop said, if it doesn't happen today...