Totally untrue. Israel unilaterally disengaged from Gaza in 2005 [1]. The current divides aren't as entrenched as the belligerents would have us believe.
[1] https://en.wikipedia.org/wiki/Israeli_disengagement_from_the...
> Bernard Avishai states that the Gaza withdrawal was designed to obviate rather than facilitate peace negotiations [...]
> Prime Minister Ariel Sharon's senior adviser, Dov Weissglass, explained the meaning of Sharon's statement further: The significance of the disengagement plan is the freezing of the peace process, and when you freeze that process, you prevent the establishment of a Palestinian state [...]
> Shimon Peres, then Vice Prime Minister, stated in an interview that: "We are disengaging from Gaza because of demography"