By Nadine Yousif, BBC
Israel is the largest recipient of US military aid. Photo: AFP / BRENDAN SMIALOWSKI
US President Joe Biden has said that countries receiving American weapons must adhere to international law in a memorandum issued on Thursday night.
The executive order requires foreign governments receiving military aid to provide written assurances that they are abiding by the laws of war.
The move comes after the president admitted Israel had gone "over the top" in its response in Gaza.
Since 1950, Israel has received more US military aid than any other nation.
In the memorandum, President Biden said that "credible and reliable written assurances" must be provided to the US by foreign governments that receive American weapons to ensure were are used in accordance with international law.
As part of this, foreign governments must also provide assurances that US humanitarian aid was being delivered to civilian populations caught in a conflict.
The memorandum requires this information be shared with Congress periodically, as well as the US president.
All 100 countries receiving US weapons must sign the assurances in the next 180 days. But those involved in active conflicts, including Israel, have just 45 days to reply to the order.
If an issue arises, a plan must be put in place to remediate the situation, the memorandum stated.
"Such remediation could include actions from refreshing the assurances to suspending any further transfers of defence articles or, as appropriate, defence services," it said.
Washington sends around $3.8 billion ($NZ6.18 billion) in military aid to Israel each year, making the country the world's biggest recipient of such funding.
While administration officials told reporters in a briefing on Thursday that the order did not target any particular country, it comes after prominent Democratic lawmakers raised concerns about Israel's military campaign in Gaza and whether it has adhered to international law.
Senator Chris Van Hollen, who has led the the push in Congress to order countries in receipt of military aid to be forced to follow international law, welcomed the move.
"I believe this will give more leverage [to Biden] to ensure all recipients of US military assistance, including the Netanyahu government, will abide by international humanitarian law and cooperate more in the delivery of humanitarian assistance," Van Hollen said.
Israel's military campaign was prompted by an October 7 Hamas attack on Israeli territory that killed 1,300 people, according to Israeli officials. Another 250 people were taken hostage.
Since Israel's retaliatory offensive, more than 27,800 Palestinians have been killed and at least 67,000 have been injured, according to the Hamas-run health ministry.
Aerial footage of Gaza shows that at least half of the besieged territory's buildings have been damaged or destroyed. About 1.7 million people - more than 80% of Gaza's population - are displaced.
The flow of aid to Gaza's civilian population has also been significantly limited since the start of the war in October, with UN officials warning repeatedly that many are at the risk of famine.
Earlier this week, Israeli Prime Minister Benjamin Netanyahu said the military has been told to prepare to operate in Rafah, a city bordering Egypt where 1.5 million Palestinians have been sheltering.
Netanyahu added that "total victory" by Israel over Hamas was just months away.
In response, the US warned on Thursday that staging a military offensive into the city without proper planning would be a "disaster".
The White House added that it would not support major operations without due consideration for the refugees there.
On Friday, Netanyahu said he ordered the Israeli military to prepare a plan to evacuate the population of Rafah ahead of its expected invasion.
He said he asked officials to present a "double plan" that would include the evacuation of civilians and a military operation to "collapse" remaining Hamas militant units.
This story was first published by the BBC.