Since Israel controls the airspace, the water and the border with Gaza, neighboring countries see the risk that refugees would not be allowed to return after the war, says Rouzbeh Parsi.

"It could even appear that they are helping Israel expel Palestinians, which they don't want. In addition, there are no logistical conditions to house 1.5 million refugees, says Parsi.

The U.S. can make a difference

The only people who could get Israel to sign some kind of agreement that refugees from Gaza would be allowed to return after the war would be the United States, Parsi said. But it has not shown that level of influence on Israel before.

So far, Egypt has received only a few people from the Gaza Strip, including the wounded in need of medical care and foreign nationals to be evacuated.

In addition to the concern that refugees would not be allowed to return, the country has more concerns.

"They don't want Hamas fighters coming in who can create problems in Egypt but also for Israel from Egypt.

Such an outcome would even risk Egypt being drawn into the war, according to political scientist Anders Persson.

Will demand a Palestinian state

In neighboring Lebanon and Jordan, the history of displaced Palestinians is even more tangible.

"Lebanon already has many Palestinian refugees from previous wars who are now living in refugee camps. The hope has been expressed that they will be able to return to their homeland, but it will most likely never happen, says Rouzbeh Parsi.

Lebanon's unstable economy is also affecting the country's capabilities.

Jordan's population is largely made up of Palestinians. Many came to the country after the wars of 1948 and 1967.

"I don't think you would be able to handle the domestic political pressure if new refugees are allowed in without a guarantee of return. In the end, I think they will demand a Palestinian state.