The Obama administration will provide food and medicine to Syrian rebel fighters, Secretary of State John F. Kerry said Thursday, announcing a cautious U.S. foray into front-line battlefield support that falls far short of the heavy weapons or high-tech gear the rebels seek.

“The stakes are really high, and we can’t risk letting this country — in the heart of the Middle East — be destroyed by vicious autocrats or hijacked by the extremists,” Kerry said following discussions among a group of Western and Arab nations that are funding, and in some cases arming, the fighters.

The United States will, for the first time, send supplies through the rebels’ central military headquarters, with U.S. advisers supervising the distribution of food rations and medical supplies, U.S. officials said. The shift is intended to give the U.S.-backed Syrian Opposition Coalition greater say over the aid, but it is also a test of the rebels’ ability to keep donated supplies out of the hands of extremists in their midst.

Washington also will send an additional $60 million to help the umbrella Syrian Opposition Coalition provide basic services such as sanitation and education in areas the rebels now control, Kerry said. That is on top of about $50 million spent on indirect help for the opposition. The goal of the new money is to counter the increasingly effective network of services provided by militants.

Kerry called President Obama’s decision to expand U.S. support “a significant stepping-up of the policy.”

Britain and other nations working in concert with the United States are expected to go further to help the rebel Free Syrian Army by providing battlefield equipment such as armored vehicles, night-vision devices or body armor. The Obama administration is weighing similar assistance, but Kerry announced only the first, small steps.

The United States is one of about a dozen nations prepared to provide broader financial and practical support for the rebels fighting to oust Syrian President Bashar al-Assad. Kerry and other diplomats framed the new help during meetings with Syrian political opposition leaders Thursday in Rome.

Standing alongside Kerry in a joint appearance before reporters, the leader of the Syrian Opposition Coalition had no words of thanks for an offer that still represents a hedge of the U.S. bet on the group it helped to form last year.

Coalition chairman Mouaz al-Khatib angrily appealed for a humanitarian corridor to the besieged city of Homs and said the rebels are tired of Western complaints about extremists in their ranks. He argued that the real enemy is the Assad regime but said too many outsiders are worried only about “the length of a beard of a fighter.”

“No terrorists in the world have such a savage nature as those in the regime,” Khatib said in Arabic.

The Syrian opposition leader’s finger-jabbing anger was in marked contrast to Kerry’s clipped and measured tone. Kerry looked at Khatib without expression as the Syrian spoke.

Kerry said Assad is “out of time and must be out of power.” But U.S. officials acknowledged that Assad has shown little sign that he is ready to bargain with the rebels.

The rebels have captured significant territory and large caches of military weapons, but the two-year war that has killed about 70,000 people remains mostly a stalemate.

Kerry said he is confident that, combined with other nations’ new offers, the U.S. assistance will make a difference.

“The totality of this effort is going to have an impact on the ability of the Syrian opposition to accomplish its goals,” Kerry said. He promised to take other rebel requests to Washington for further discussion.

The Obama administration and its leading European allies, including Britain and France, have sought to coordinate their assistance to the rebels, and Kerry will now head to Turkey, Saudi Arabia, the United Arab Emirates and Qatar to try to ensure that all countries providing aid are working from the same game plan. The Saudis have taken the lead in sending weapons to opposition fighters.

Like the rebels themselves, Saudi Arabia would prefer that the United States move toward a military intervention. Although U.S. officials indicated additional aid would be forthcoming, the administration is still opposed to sending weapons or using its aircraft to stop Assad’s air bombardments. Discussions are ongoing in Washington to determine how much further the administration is willing to go, including expansion of a minimal military training program.

In a tweet following the Rome meeting, British Foreign Secretary William Hague said Britain will “be announcing new assistance.”

Britain and France have been awaiting an easing of a European Union arms embargo on Syria that will go into effect Friday. The new terms allow individual E.U. members to provide “non-lethal and technical assistance to protect Syrian civilians.” Each member country is left to decide what form its aid will take.

British and French officials have indicated that their support of the rebel forces might also include training, coordinated with allies and conducted outside Syria.

Another opposition figure, Adib Shishakly, who is in charge of coordinating humanitarian assistance for the National Coalition for Syrian Revolution and Opposition Forces, cautiously welcomed the U.S. announcement.

“We expected more, but hopefully this is a positive start,” he said, speaking from the coalition’s headquarters in Cairo. However, he added, the opposition is “absolutely disappointed” that the United States is not offering military assistance to the Free Syrian Army at a time when the Syrian government is escalating its use of force to include ballistic missiles as well as airstrikes.

“They’re not doing anything about the Scuds,” Shishakly said, referring to the Syrian military’s increasing use of Russian-designed missiles. “And if they are not going to do anything about it, at least give us the tools to protect ourselves.”

Rebels and analysts said the real significance of the aid is that a portion will go directly to the Free Syrian Army’s military councils, opening a formal channel between the U.S. government and the rebels for the first time.

The councils were formed at the prodding of U.S. officials last year in an effort to make the ad hoc rebel army more effective by giving it a more coherent structure. But the councils have had limited success in coordinating the hundreds of rebel groups that have emerged to join the fight, among them some of the increasingly powerful Islamist groups that have chosen not to join the councils.

A spokesman for the Damascus Military Council who goes by the nom de guerre Abu Qatada said he was deeply disappointed that the assistance package did not include arms.

“We thank the American government for the aid,” he said in an interview over Skype. “However, we would like to point out that we do not need food at the moment. We would rather have weapons to defend ourselves and our children.”

If the assistance is intended to increase U.S. influence over the chaotic events unfolding on the battlefield, “it will need a lot more than this,” said Salman Shaikh, director of the Brookings Doha Center in Qatar. “The trajectory of the conflict is much more dangerous than that, and these kind of Band-Aids are not going to have a major impact on the ground.”

DeYoung reported from Washington. Liz Sly and Ahmed Ramadan in Beirut and Anthony Faiola in London contributed to this report.