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Since October 7, Israel and western countries have tried to curb Hamas's international financing networks, hoping to hinder its ability to conduct further attacks.
The precise inner workings of the group's finances are kept secret, but analysts have collated estimates.
Here, The National breaks them down:
Who is funding Hamas?
As a US and EU-designated terrorist entity, Hamas is excluded from receiving the official aid that the US and the EU provide to the Palestinian Liberation Organisation (PLO) in the occupied West Bank.
Before taking over the Gaza Strip in 2007, Hamas relied primarily on funding from Iran, other state sponsors including Syria and Sudan, and charities including crowdfunding campaigns, with a portion of funds sent through cryptocurrency.
Once it controlled the enclave, the organisation generated income by imposing taxes on items transported via an extensive network of tunnels, bypassing the official crossing point at the Egyptian border with Gaza.
It also imposed taxes on civilians and companies in addition to initiating fees for the registration of vehicles, licences, electricity, water and birth certificates.
According to experts, Hamas earned roughly between $350 million and $630 million a year through taxation, extortion, border control and other means related to controlling the enclave.
Taxes represented the largest portion of Hamas financing, Jessica Davis, president of the Canadian group Insight Threat Intelligence, said in a report on Hamas financing.
These were followed by donations from Qatar, evaluated at $180 million, Iran ($100 million) and investments ($20 million), according to Ms Davis.
Which countries are contributing?
Since its formation in 1987, Hamas was and remains one of Iran's biggest benefactors, with Tehran contributing funds, weapons and training.
Experts say Iran's support varies from $70 million to $120 million annually.
“Iran provides these funds through Iran’s Islamic Revolutionary Guard Corps' Quds Force and these funds are likely provided directly to Hamas’s armed wing, the Ezzedine Al Qassam Brigades,” Ms Davis wrote.
Turkey has been another strong Hamas supporter and does not consider it a terrorist group.
Brian Nelson, the US Treasury's undersecretary for terrorism and financial intelligence, said in November that Ankara has long played a “prominent role” in allowing Hamas access to funds.
Turkish President Recep Tayyip Erdogan pushed back against mounting US pressure to cut Ankara's historic ties with Hamas in the wake of the militants' October 7 attacks on Israel.
As for Qatar, it began making monthly payments in 2018 to the Gaza Strip, delivering cash-filled suitcases – with Israel's approval – to pay employee salaries, provide humanitarian aid and run social services in Gaza.
The payments started after the Palestinian Authority in the West Bank decided to cut the salaries of government employees in Gaza in 2017.
In a speech at the University of Valladolid in Spain, the EU's top diplomat Josep Borell said Israel had financed the creation of Hamas in a bid to weaken the Palestinian Authority.
“Yes, Hamas was financed by the government of Israel in an attempt to weaken the Palestinian Authority led by Fatah,” Mr Borrell said without elaborating.
Israeli Prime Minister Benjamin Netanyahu has denied accusations that his government spent years actively boosting Hamas in Gaza.
Experts told The National that Qatar, which also hosts Hamas in Doha, has enabled the transfer of millions of dollars to charitable organisations linked to the group.
How does Hamas invest its money?
Hamas diversifies its funds by investing in business ventures, a strategy that helps conceal the source and whereabouts of its finances.
According to experts, Hamas’s investment portfolio includes about 40 companies, mostly in the construction and real estate sectors in countries including Turkey, Qatar, Algeria and Sudan.
The Turkey-based Hamas investment office, which holds assets worth more than $500 million, according to the US Treasury, oversees day-to-day portfolio management.
Hamas also relies on numerous intermediaries to conduct financial activities covertly for the group and its informal financial system, like money exchange houses, which are used to move funds.
Cryptocurrency has also played an important role in moving Hamas funds.
“Hamas did use crypto largely not to generate money but mostly as a means of moving money largely for crowdfunding campaigns,” said Matthew Levitt, Fromer-Wexler fellow and director of the Reinhard Programme on Counterterrorism and Intelligence at The Washington Institute.
Ms Davis wrote: “The amount transferred could be significant, with some estimates stating that Hamas had received $41 million between August 2021 and June 2023, often through small-dollar donations.”
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