Israel conflict: How has Hamas grown a rocket arsenal?

In this fourth war between Israel and Gaza’s Hamas rulers, the Islamic militant group has fired more than 4,000 rockets at Israel, some hitting deeper in Israeli territory and with greater accuracy than ever before. 

The unprecedented barrages reaching as far north as the seaside metropolis of Tel Aviv, coupled with drone launches and even an attempted submarine attack, have put on vivid display a homegrown arsenal that has only expanded despite the chokehold of a 14-year Israeli-Egyptian blockade. 

"The magnitude of (Hamas) bombing is much bigger and the precision is much better in this conflict," said Mkhaimar Abusada, a professor of political science at Al-Azhar University in Gaza City. "It’s shocking what they’ve been able to do under siege." 

Israel has argued that the blockade — which has caused severe hardship for more than 2 million Palestinians in Gaza — is essential for preventing a Hamas arms build-up and cannot be lifted. 

Here’s a look at how, under intense surveillance and tight restrictions, Hamas managed to amass its cache. 

FROM CRUDE BOMBS TO LONG-RANGE ROCKETS 

Since the founding of Hamas in 1987, the group's secretive military wing — which operates alongside a more visible political organization — evolved from a small militia into what Israel describes as a "semi-organized military." 

In its early days, the group carried out deadly shootings and kidnappings of Israelis. It killed hundreds of Israelis in suicide bombings during the second Palestinian intifada, or uprising, which erupted in late 2000. 

As violence spread, the group started producing rudimentary "Qassam" rockets. Powered partly by molten sugar, the projectiles reached just a few miles, flew wildly and caused little damage, often landing inside Gaza.