IN THE evening of July 16th the BBC reported that Israel would observe a "humanitarian ceasefire" for five hours on July 17th. That is unlikely to spell the end of hostilities. Hamas apparently rejected Egypt’s ceasefire plan on July 15th, and there is little likelihood of Israel agreeing to Hamas's conditions for ending the war. Perhaps only exhaustion will bring the current round of fighting to a halt. Or Hamas and Palestinian Islamic Jihad, its main rival in Gaza, may soon exhaust their supply of rockets. But when that might happen depends on how many rockets they had to start with, and how swiftly Israel destroys their missile arsenals. The data that exists comes from the Israel Defence Forces (IDF), and there is good reason to believe this count is fairly accurate given their regular surveillance of the region. When Operation Protective Edge got under way, the IDF estimated that there were about 11,000 rockets in Gaza, 6,000 of them controlled by Hamas and most of the rest by Islamic Jihad. Of these, missiles with a range of around 75km (putting Tel Aviv within reach), such as the Iranian Fajr-5 and its locally constructed variant the M-75, numbered about 600 (nearly all in the hands of Hamas). There were also few—probably no more than 100—longer-range and more powerful Syrian M-302 missiles that can reach as far as Haifa in the north, probably supplied by Hizbullah, the Iranian-backed militia in Lebanon.

An average of 160 missiles a day, 80% of them shorter-range Grad rockets, have been fired into Israel since July 8th—a total of about 1,400 as of July 17th. At the same time, the IDF claims to have “degraded Hamas’ military capability by 30-40%”. Quite what that means is unclear. Israeli jets have targeted what the IDF calls “operational infrastructure”. That includes missile launchers (prioritising longer-range systems), command and control centres, stored missiles and missile-production sites. If the IDF's claims are accurate, about half of the Hamas/Islamic Jihad inventory may be left.

Before the current operation, Hamas was thought to be producing some 30 medium-range missiles a month using components smuggled in from Iran and Syria. That is quite a significant quantity given that Egypt in recent months has shut or destroyed around 95% of the tunnels on its side of the border, and little coming from the sea gets past Israeli patrol boats. However, under Israel’s bombardment it is likely that production has now been drastically slowed.

Simply extrapolating the current tempo of operations on both sides would suggest that missile stocks in Gaza will be getting very low within a fortnight. However, that assumes that Israel is not running out of targets, as it did after only a week of Operation Pillar of Defence in 2012. The IDF says that it still has plenty of targets to work on, but the pressure to find more if the missiles keep on coming could yet lead to a limited ground assault. That is something Israel still wants to avoid. But the problems for Hamas and Islamic Jihad are more acute. They need to find a way of quitting while they retain some firepower, particularly as building a new arsenal of rockets will be much harder than before given the close security co-operation between the new al-Sisi government in Egypt and Israel. The military logic on both sides suggests that the end of this bout of fighting is not far off.