As the Saudi-Arabia-led coalition escalates its military assault on Yemen following the dissolution of a fragile ceasefire, human rights campaigners are calling on lawmakers to urgently intercede to block a massive U.S. arms sale to the Gulf monarchy and help stem large-scale war crimes.

The U.S. State Department announced last week that it has approved a $1.15 billion deal to ship military equipment and weapons to Saudi Arabia, including tanks, machine guns and grenade launchers. This deal comes on top of the more than $20 billion in weapons that the U.S. has shipped to Saudi Arabia since March 2015, when the coalition began its military campaign.

Following state department approval, Congress has only 30 days to block or change the deal. Given that lawmakers are now in the midst of their summer recess, this timeline means they will have to act urgently following Labor Day weekend—if they muster the will to take action all.

Now, the advocacy groups Oxfam, Just Foreign Policy and Code Pink are pressing members of Congress find that will. Nearly 6,000 people have signed a petition that calls on Congress to “Force a public debate on U.S. participation in the Saudi war in Yemen by advocating for blocking the planned transfer of U.S. tanks and armored vehicles to Saudi Arabia.”

If approved without debate, the shipments would be in line with long-standing U.S. practice. According to a report released by the Stockholm International Peace Research Institute (SIPRI), the United States has been the world’s top exporter over the past five years, with the Middle East the top recipient of American arms and Saudi Arabia the number-one importer.

However, Robert Naiman, policy director for Just Foreign Policy, told AlterNet that there is a slim hope that this deal could go differently. Earlier this summer, the U.S. House of Representatives came surprisingly close to barring the transfer of U.S. cluster bombs to Saudi Arabia. Both Human Rights Watch and Amnesty International report that the Saudi-led coalition is dropping U.S.-manufactured cluster bombs on civilian areas, killing and maiming civilians, including children.

“The fact that we almost won two months ago in the House on banning the transfer of cluster bombs to Saudi Arabia suggests that blocking this sale could be more plausible than a lot of people in the Beltway seem to think,” said Naiman.

In approving the arms deal, the state department claimed, "This proposed sale will contribute to the foreign policy and national security of the United States by helping to improve the security of a strategic regional partner which has been and continues to be a leading contributor of political stability and economic progress in the Middle East."

In reality, the nearly-17-month military assault is unleashing a humanitarian nightmare on the people of Yemen, this week alone killing over a dozen civilians at a potato chip factory and bombing the main bridge between the port city of Hodeidah and capital Sanaa, cutting off a critical transport line for food and fuel. Throughout the campaign, coalition bombs have rained down on factories, weddings and even a center for the blind. The Saudi-led coalition is responsible for the majority of more than 3,500 civilians who have been killed since March 2015.

Furthermore, all evidence indicates that the coalition attacks have opened up space for the Yemen-based al Qaeda in the Arabian Peninsula (AQAP) to gain territory and power. Meanwhile, journalist Safa Al Ahmad has unearthed evidence that elements of the Saudi-led coalition have even fought in alliance alongside militants affiliated with Al Qaeda.

Scott Paul, a senior policy adviser at Oxfam America, told Foreign policy that yet another massive sale of arms would signal that the U.S. is "all-in on a senseless war that has created one of the world’s largest humanitarian emergencies.”

To fully address the U.S. role in driving this emergency, it is necessary to look beyond arms shipments. The Obama administration has deployed troops, assisted the coalition in identifying bomb targets and conducting “intelligence” and sent warships to enforce the naval blockade that has choked off critical imports, contributing to a crisis that has left at least 21 million people in desperate need of food. The U.S. is one of at least a dozen countries participating in or backing the coalition, including: Saudi Arabia, Egypt, Morocco, Jordan, Pakistan, Sudan, United Arab Emirates, Kuwait, Qatar, Bahrain and Britain.

The Saudi-led military coalition is waging its attacks armed with U.S. weapons, as well as with effective immunity from the United Nations. As recently as June, UN Secretary-General Ban Ki-moon admitted that he scrubbed the Saudi-led coalition in Yemen from a "list of shame" of armed forces that violate the rights of children because Saudi Arabia threatened to pull its funding from key programs as a retaliatory measure.