ISTANBUL (AP) — The United States said Sunday that it will double its non-lethal assistance to Syria's opposition as the rebels' top supporters vowed to enhance and expand their backing of the two-year battle to oust President Bashar Assad's regime.

Yet the pledge fell far short of what the opposition had made clear it wanted: weapons and direct military intervention to stop the violence that has killed more than 70,000 people. The Syrian National Coalition had sought drone strikes on sites from which the regime has fired missiles, the imposition of no-fly zones and protected humanitarian corridors to ensure the safety of civilians.

Instead, the Obama administration's pledged to provide an additional $123 million in aid, which may include for the first time armored vehicles, body armor, night vision goggles and other defensive military supplies. It was the only tangible, public offer of new international support as the foreign ministers of the 11 main countries supporting the opposition met in a marathon session in Istanbul.

U.S. Secretary of State John Kerry announced the new package of assistance in a written statement at the conclusion of the conference that began Saturday afternoon and stretched into early Sunday.

The additional aid, which brings total non-lethal U.S. assistance to the opposition to $250 million since the fighting began, "underscores the United States' firm support for a political solution to the crisis in Syria and for the opposition's advancement of an inclusive, tolerant vision for a post-Assad Syria," he said.

Kerry said a portion of the new money would be used to follow through on President Barack Obama's recent authorization to expand direct supplies to the Free Syrian Army beyond food and medical supplies to include defensive items. Officials said the exact types of supplies would be decided in consultation with allies and the rebels' Supreme Military Council.

Kerry also announced nearly $25 million in additional food assistance for Syrians who remain inside the country as well as those who have fled to neighboring countries, bringing the total U.S. humanitarian contribution to the crisis to more than $409 million.

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While pleased with the U.S. moves, the opposition appeared deeply disappointed, especially as it lost some ground in the latest clashes with Syrian troops backed by pro-government gunmen capturing at least one village in a strategic area near the Lebanese border.

"We appreciate the limited support given by the international community, but it is not sufficient," it said in a statement released at the end of the conference. "We call on the international community to be more forthcoming and unreserved to fulfill its responsibilities in extending support that is needed by the Syrian people."

Ahead of the meeting, the opposition said it wanted guns and ammunition. And, it said it wanted its friends to conduct drone strikes on Syrian territory to take out Assad's missile capabilities and renewed appeals for the creation of no-fly zones and safe corridors.

"The technical ability to take specific action to prevent the human tragedy and suffering of innocent civilians, mostly women and children, is available in the form of specific intelligence and equipment," it said. "Syrians understand that such ability is within the reach of a number of members of the Friends of Syria group, yet nothing serious has been done to put an end to such terror and criminality."

But none of those calls were specifically addressed by the foreign ministers in a joint statement of their own. Instead, they referred only to their recognition of the "need to change the balance of power on the ground." They said they would welcome additional pledges and commitments to the Free Syrian Army and delegated the rebels' Supreme Military Council to be the conduit for all military aid.

European nations are considering changes to an arms embargo that would allow weapons transfers to the Syrian opposition. But European Union action is unlikely before the current embargo is set to expire in late May.

Britain and France have been leading the calls to amend the embargo to test the strategy that merely giving its members permission to supply arms may cause Assad to rethink his calculation to hold on to power. But some in the EU, notably Germany and the Netherlands, are reluctant, believing that more weapons flowing into Syria will only increase the bloodshed and that they could fall into the hands of extremists.

In what appeared to be an attempt to soothe those fears, the opposition affirmed its commitment to an inclusive and pluralistic democracy that condemns extremism.

"Our revolution is for the entire Syrian people," opposition leader Moaz al-Khatib told reporters, standing alongside Kerry and Turkish Foreign Minister Ahmet Davutoglu.

The opposition also pledged in its statement that any military hardware it receives will be used responsibly.

"We will guarantee that weapons will be used in accordance with the specific purpose that they were supplied for, and that these weapons will not fall in the wrong hands," it said. "These weapons and military equipment will be returned to the relevant and appropriate institutions upon the conclusion of the revolution."

Obama has said he has no plans to send weapons or give lethal aid to the rebels, despite pressure from Congress, some administration advisers and the appeals from opposition. There are no plans to change that policy, although U.S. officials say they are not opposed to other countries sending arms as long as the recipients have been properly vetted.

But since February, the U.S. has shipped food and medical supplies directly to the Free Syrian Army and Kerry's announcement marked the first time that Washington has acted on Obama's recent authorization to expand that aid.

The U.S. and its European and Arab allies are struggling to find ways to stem the escalating violence that has led to fears that chemical weapons may have been used.

The foreign ministers urged an immediate investigation by the United Nations to substantiate claims that chemical weapons had been used. "If these allegations are proven to be correct, there will be severe consequences," they said in their statement.