The restrictions on movement and goods in the Gaza Strip imposed by Israel date to the early 1990s. After Hamas took over in 2007, Israel significantly intensified existing movement restrictions and imposed a complete blockade on the movement of goods and people in and out of the Gaza Strip. In the same year, Egypt closed the Rafah border crossing. The blockade's stated aims are to prevent the smuggling of weapons into Gaza and exert economic pressure on Hamas. While the blockade's legality has not been adjudicated in court, human rights groups believe it would be deemed illegal and that it is a form of collective punishment, as it restricts the flow of essential goods, contributes to economic hardship, and limits Gazans' freedom of movement. The land, sea, and air blockade isolated Gaza from the rest of the occupied Palestinian territory and the world. The blockade and its effects have led to the territory being called an "open-air prison". Exit and entry into Gaza by sea or air is prohibited. There are only three crossings in and out of Gaza, two of them controlled by Israel and one by Egypt. Israel heavily regulates Palestinians' movement through Erez, with applications considered only for a small number of laborers (less than 5% of the number considered in 2000) and for limited medical and humanitarian reasons. Israel's military cooperation with Egypt and its control of the population registry (through which it controls who can obtain the necessary travel documents) gives it influence over movement through Rafah. Imports are heavily restricted, with "dual use" items permitted only as part of donor projects. This includes construction material and computer equipment. Exports are also heavily restricted, with the main impediment to economic development in Gaza being Israel's ban on virtually all exports from the Strip. Israel blockaded the Gaza Strip at various levels of intensity in 2005–2006. Israeli-imposed closures date to 1991. In 2007, after Hamas seized control of the Gaza Strip, Israel imposed an indefinite blockade of Gaza that remains in place, on the grounds that Fatah and Palestinian Authority forces had fled the Strip and were no longer able to provide security on the Palestinian side. Israel has said the blockade is necessary to protect itself from Palestinian political violence and rocket attacks, and to prevent dual use goods from entering Gaza. Israel has been accused of violating or failing to fulfill specific obligations it has under various ceasefire agreements to alleviate or lift the blockade. "Crossings were repeatedly shut and buffer zones were reinstated. Imports declined, exports were blocked, and fewer Gazans were given exit permits to Israel and the West Bank." Human rights groups, international community representatives, and legal professionals have decried the blockade as a form of collective punishment in contravention of international law, specifically the Fourth Geneva Convention. Rights groups have held Israel mainly responsible as the occupying power.