Hamas just upgraded their Qassams and built them up into a stockpile so that they can launch a Hezbollah-like saturation bombing of Israeli civilian centers. Over the past few months they've prepared an elaborate bunker system to slow any Israeli retaliation and inflict maximum casualties:

When firing rockets is politically inconvenient, Hamas hands them over to smaller organizations such as the Islamic Jihad, various Fatah factions and the Popular Resistance Committees to launch them in its place. In previous periods of escalation between Israel and Hamas, such as last year's Independence Day, Hamas fired almost 300 rockets in a few days before running out of supplies. The defense establishment is now concerned that Hamas may accumulate several hundred or even thousands of rockets, building up a large arsenal. Under this scenario, Hamas would be able to fire hundreds of rockets a day at Sderot for several days, prompting Israel to take extreme measures.

And you know who's going to help them? Help them despite being given $410 million in new US security assistance, $5 billion in European aid, and cutting edge APCs from Russia to "bolster Abbas against Hamas"? Of course:

The officials told The Jerusalem Post that the talks, which are due to begin next week, according to the Annapolis peace conference, would be called off if the IDF invaded the Gaza Strip. Meanwhile, Kadoura Fares, a top Fatah operative in the West Bank, confirmed that his faction was planning to fight alongside Hamas's forces if the IDF sent troops into the Gaza Strip. Earlier this week, the Post revealed that Fatah leaders had decided to join with Hamas to fight against the IDF inside Gaza. "Fatah will fight alongside all the Palestinian groups against the Israeli army when it invades the Gaza Strip," Fares said. "In such a case, Hamas won't be left alone in the confrontation with Israel."

On the plus side, if the Israelis want to know anything about the weapons being used against them they can just ask Russia or the US State Department for the schematics.

Oh, and just for completions' sake:

At the meeting, Abbas, too, expressed deep concern over reports that the IDF might attack the Gaza Strip. He warned that such a move would deal a severe blow to efforts to resume peace talks between Israel and the Palestinians. He added that the PA had appealed to several countries, including the US, to exert pressure on Israel to refrain from launching a military operation.

Naturally.

References:
* Defense officials concerned as Hamas upgrades Qassam arsenal [Ha'aretz]
* Hamas Has Smuggled 112 Tons Of Explosives Into Gaza, Preparing Bunker System For All Out War (Plus: Israel Suspends Decision To Cut Fuel On Humanitarian Grounds) [MR]
* US Unveils $410 Million's Worth Of Assistance That Will Shortly Be Seized By Hamas [MR]
* PA Police Getting More Than $5 Billion In New Aid To Use Against Israeli Civilians, Lose To Hamas [MR]
* PA To Get 25 Shiny Helicopter Busting APCs Next Week [MR]
* PA: Gaza op would ruin peace plans [JPost]

Previously:
* Abject Failure Keith Dayton Moves Goalposts To Justify US Security Assistance, Lets Abbas Try Again
* Simple Equation - More Aid To Palestinians Means More Murders A Year Later
* PA Police Officers Rolling In Millions Of New US Aid, Murdering Israeli Civilians