Israel is supporting armed groups of Palestinians in Gaza in what it says is a move to counter Hamas. But officials from the U.N. and aid organizations say the military is allowing them to loot food and other supplies from their trucks.

The attempt to block the flotilla carrying the famed climate activist comes 15 years after a similar aid effort ended in deadly violence.

It is almost 20 months since Israel launched a military campaign in Gaza in response to the Hamas-led cross-border attack, in which about 1,200 people were killed and 251 others were taken hostage. At least 54,677 people have been killed in Gaza during the war, according to the territory's health ministry.