As the Israel-Hamas war enters its second month, the militant group's sources of funding are coming under closer scrutiny. The US has signalled its intent to impose fresh sanctions not just on Hamas members, but financial facilitators affiliated to the militant group. However, crippling the network won't be easy. Behind Hamas lies a complex financial web that draws from taxing Palestinians in Gaza, a vast investment portfolio with assets spread across several countries in the region and, crucially, key international donors, including countries such as Iran and Qatar. RUSI Senior Research Fellow Stephen Reimer features.