President Biden on Thursday issued a memorandum that lays out the standards countries that receive U.S. weapons must adhere to and, for the first time, requires the administration to submit an annual report to Congress about whether countries are meeting the requirements.

The national security memorandum comes after prominent Democratic lawmakers have raised concerns about Israel’s military campaign in Gaza and whether the country, which has received hundreds of millions of dollars worth of U.S. weapons, has adhered to international law. Nearly half of Senate Democrats have supported a measure that would ensure Israel and other countries are held accountable for meeting those standards.

The memorandum does not include new guidelines or conditions but instead calls for the State Department to receive written assurances from countries receiving U.S. weapons that they will abide by existing U.S. standards. Those include abiding by international law and facilitating transport of U.S. humanitarian assistance.

The memorandum comes just as Israeli Prime Minister Benjamin Netanyahu announced that the Israeli military will continue its Gaza campaign in Rafah, where more than 1 million Palestinians have fled for safety under Israeli guidance. On Thursday, White House spokesman John Kirby said any Israeli operation in Rafah under the current circumstances “would be a disaster for those people, and we would not support it.”

Israel launched its punishing military campaign in Gaza after Hamas militants on Oct. 7 rampaged through the border fence and killed 1,200 Israelis, many of them civilians, and took about 250 others hostage. Israel’s military operations have killed more than 27,000 Palestinians in Gaza, and its siege of the enclave — in which it has cut off most access to food, water, electricity, medicine and other basic goods — has created a humanitarian catastrophe that has put hundreds of thousands of people at risk of famine, according to the World Food Program.

Israeli protesters have blocked aid trucks from going into Gaza and the United States has for months pressed Israel to allow more aid into the enclave.

The memorandum also comes as the Senate began voting on a $95 billion foreign aid package on Thursday that includes $14 billion in aid to Israel, as well as money for Ukraine and Indo-Pacific allies.

Sen. Chris Van Hollen (D-Md.) has led a push to amend the foreign aid bill to state that any country receiving the aid must follow international law, which has attracted 18 co-sponsors, including senators representing purple states such as Georgia and Wisconsin. He will pull support for that amendment, avoiding a vote that could look like a rebuke of how the Biden administration has handled its ally during the war.

The memorandum goes farther than Van Hollen’s amendment in that it includes an enforcement mechanism of sorts, where the president must take action if the secretary of state informs him a country is not in compliance. That action could include suspending military aid, but could also be a less drastic step.

“What this does is create an accountability structure,” Van Hollen said. “This is a very big deal. I applaud the president for taking historic action.”

Van Hollen and other Democratic senators have raised alarms about the way Netanyahu has prosecuted the war, as thousands of civilians have been killed in what Biden once described as “indiscriminate bombing,” and aid into the devastated region has been stalled by the Israeli government.

“I believe this will give more leverage [to Biden] to ensure all recipients of U.S. military assistance, including the Netanyahu government, will abide by international humanitarian law and cooperate more in the delivery of humanitarian assistance,” he said.

A senior administration official stressed that the White House was not issuing the memorandum because it felt any country was violating existing standards. The official, who spoke on the condition of anonymity to speak candidly, said the administration is having regular conversations with Israel about limiting civilian casualties, adhering to international law and allowing more humanitarian aid to Gaza but did not believe the country was failing to meet U.S. standards.

“This lets the whole world in to that conversation,” the official said of discussions with Israel. “In addition to the conversation with the Israelis, it’s a way to convey in one place … this is something we value and expect in particular of countries that receive our weapons. That shouldn’t be new to anyone because it’s been policy, but I do think it’s important to set that out clearly.”

The memorandum also requires the State Department and Department of Defense to make an assessment of whether any country is using weapons in a way not consistent with best practices for reducing civilian harm. The first report is due to Congress in about three months, and then reports will be due once a year.