FDD:
Israeli customs authorities revealed on September 14 [2023] that their agents intercepted 16 tons of explosive material on its way from Turkey to the Gaza Strip in July. [...]
According to the Israeli Tax Authority spokesperson, the customs agents in Ashdod inspected two containers that were supposed to contain 54 tons of gypsum — the key ingredient in plaster. After testing the material in a lab, authorities concluded that some of the bags contained ammonium chloride — a dual-use chemical used in making rockets.
“The origin of this shipment cannot be ignored. Turkey has become a major sponsor of Hamas in recent years and a major hub of Hamas operations. Did the government in Ankara know about this effort to arm the terrorist group with 16 tons of explosive material? This is a crucial question to answer for Israel but also for the United States and many of Turkey’s other NATO allies.” — Jonathan Schanzer, FDD Senior Vice President for Research
Were 16 tons of "explosive material" sent from Turkey to Hamas, in that one shipment?
FWTW, Hamas has denied the claim, calling it "fabrication".