The US will start airdrops of food and emergency supplies into Gaza in the next few days, Joe Biden has announced, amid UN warnings of famine and after Israeli troops opened fire on Gazans seeking food aid.

The use of airdrops is a spectacular but inefficient way of delivering aid, and Friday’s announcement suggests that Biden had given up on being able to persuade Israel in the near future to coordinate a large-scale ground-based relief effort under the threat of mass starvation across Gaza.

Critics suggested it represented no more than a gesture, which obscured Biden’s reluctance to use US leverage to force Israel to be more cooperative in the delivery of humanitarian aid.

Related: Israel faces mounting pressure to investigate Gaza food aid deaths

“The loss of life is heartbreaking,” Biden said, making the announcement at the White House at a meeting with Italian prime minister, Giorgia Meloni. “People are so desperate that innocent people got caught in a terrible war unable to feed their families and you saw the response when they tried to get aid in.

“And we need to do more and the United States will do more,” the president added. “In the coming days, we are going to join with our friends in Jordan and others in providing airdrops of additional food and supplies [into Gaza].”

The Jordanian and French air forces have already made airdrops. It is a highly expensive and uncontrolled way of distributing food in the midst of a crisis, but access for food trucks has been limited and far below expectations and requirements. Hundreds of trucks of aid are stuck at Gaza’s border, unable to proceed mainly because of security concerns.

At least 112 people were reported killed on Thursday on the outskirts of Gaza City, where a crowd had formed to meet an aid convoy. The Palestinian authorities accused Israeli troops of opening fire on the crowd. The Israeli army gave a different account, saying that most of the fatalities were caused by a stampede around the aid convoy and some people being run over by the trucks. The army admitted opening fire but only on a smaller group of Palestinians who they said had threatened Israeli soldiers after the alleged stampede.

The administration at a local hospital said that 80% of the injuries it was treating were gunshot wounds, and the US, France and Germany have asked Israel to carry out an investigation.

Biden said that while it carried out airdrops, the US was looking at opening other aid corridors to Gaza, including “the possibility of a marine corridor to deliver large amounts of humanitarian assistance.”

In a worrying sign for Democrats, anxious about the 81-year-old president’s ability to handle a gruelling election campaign, he mistakenly said Ukraine twice in the course of the announcement when he meant to say Gaza.

“In addition to expanding deliveries by land, as I said, we’re going to insist that Israel facilitate more trucks and more routes to get more and more people the help they need,” Biden said. “No excuses, because the truth is [that] aid flowing to Gaza is nowhere nearly enough now. Innocent lives are on the line and children’s lives are on the line.

“We should be getting hundreds of trucks in, not just several,” he said. “And I won’t stand by, we won’t let up and we’re … trying to pull out every stop we can to get more assistance in.”

Biden and his administration have been trying unsuccessfully for months to persuade Benjamin Netanyahu to allow more aid into Gaza, but the president has opted so far not to use some of the powerful leverage the US has over Israel, including Israeli dependence on regular and substantial arms supplies.

“If the US government disavows the use of any meaningful leverage to bring the Gaza conflict to a close, it is left with desperate and inadequate measures like this to try to address the resulting humanitarian catastrophe around the margins,” Brian Finucane, a former state department lawyer now working at the International Crisis Group, wrote on X.