A new directive by US President Joe Biden appeared to ease a split among Democrats over his military support for Israel’s war in Gaza, with lawmakers on Friday (US time) praising the order authorising a swift cutoff of military aid to countries that violate international protections of civilians.

For Biden, the commitment to conditioning US military aid for Israel and other allies and strategic partners will help him shore up support among centre-left Senate Democrats for his proposed US$95 billion ($154.5b) supplemental assistance package, which is aimed primarily at military aid for Ukraine in its war with Russia and for Israel in its war against Hamas in Gaza.

Democratic senators called Biden’s directive - meant to bring breadth, oversight, deadlines and teeth to efforts to ensure foreign governments don’t use US military aid against civilians - historic.

“This is a sea-change in terms of how you approach US military aid and its impact on civilians,” Massachusetts’ Elizabeth Warren said. She spoke at a Capitol news conference with other Democrats who’d negotiated with the White House for two months on the matter, in an effort led by Maryland Senator Chris Van Hollen.

Human rights advocates said the challenge for the new directive would be the same faced by all previous efforts to withhold US weapons and funding from human rights abusers - whether administrations will actually enforce the human rights conditions against strategically important allies and partners.

President Joe Biden, pictured here meeting with German Chancellor Olaf Scholz in the Oval Office of the White House on Friday in Washington. Photo / AP

“The issue was never knowledge” of US military aid being used in violation of international law “so much as enforcement”, said Kenneth Roth, a former head of Human Rights Watch and a visiting professor at the Princeton School of Public and International Affairs.

The new order comes in what’s officially known as a presidential memorandum. Those have the force of law, although succeeding presidents can overturn them.

Biden’s order has immediate effect. It gives Secretary of State Antony Blinken 45 days to obtain “credible and reliable written assurances” from foreign recipients of US military aid that are in active conflicts, which includes Israel and Ukraine, that they are using US military assistance in compliance with international humanitarian law and human rights law and other standards.

Foreign governments that fail to provide those assurances on time would have their military aid paused. Administrations also have the option of suspending US military assistance if they deem a foreign government isn’t really complying with humanitarian law and protections, despite claiming it is.

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Other requirements include regular reports from the administration on compliance. That includes countries not actively fighting a war.

The supply of air defence systems and some other defensive gear is exempted. While supporters say the stringent language of the order will limit the ability of presidential administrations to evade the spirit of the measure, the order does allow administrations to waive the requirements in “rare and extraordinary circumstances”.

The Biden administration has frustrated some Senate Democrats during Israel’s war in Gaza by declaring a national security emergency to rush military aid to Israel, skirting the usual process of congressional notification.

The administration has also quietly lobbied against moves by independent Senator Bernie Sanders and others to attach conditions to military aid to Israel in the supplemental legislation, with the idea of pressuring Israel to do more to spare Palestinian civilians.

Nearly 28,000 Palestinians, two-thirds of them women and children, have been killed since Israel launched its military campaign in Gaza. That followed the October 7 attacks by Hamas that killed about 1,200 people in Israel.

Israeli Prime Minister Benjamin Netanyahu’s Government has not appeared to have substantially backed off on airstrikes daily claiming civilian lives, despite the pressure from the United States, its most important ally and military supporter. The US is also frustrated at Israel’s restrictions on humanitarian aid deliveries into Gaza. Biden this week said some of his strongest criticism of Israel’s conduct of the war, calling it “over the top”.

White House press secretary Karine Jean-Pierre underscored that the administration is “not imposing new standards for military aid” with the memorandum. She said it was done in the interest of improving transparency.

Jean-Pierre added that Israeli officials were briefed on the memorandum before its release.

“They reiterated their willingness to provide these types of assurances,” Jean-Pierre said.

The US already has laws - including the Foreign Assistance Act and the Leahy Law - meant to bar security assistance to governments that are serial human rights abusers. Those “are honoured in the breach”, Roth, the human rights expert, said.

“If the administration is so indifferent to existing law, it’s not clear what difference a new set of reports will make,” Roth said.

The Democratic senators said they would continue working to strengthen the new system laid out in the order.

That includes seeking funding for the additional government oversight and codifying it into legislation so it’s harder for future presidents to trash.

“This is a very big deal,” Van Hollen said. “And it will give President Biden and the United States more tools and more leverage... to ensure that US military assistance complies with American values and American” standards.