Even as the Obama administration hardens its rhetoric on Syria, members of the Syrian opposition say the United States has failed to deliver promised communications and other equipment intended to support those seeking to overthrow President Bashar al-Assad.

President Obama used his toughest language yet Monday to warn Syria that any movement or use of its chemical weapons would cross a “red line,” the closest he has come to threatening the use of force. Until now, the administration has ruled out a direct intervention and has made the provision of communications gear the centerpiece of U.S. involvement.

But opposition activists say they have smuggled hundreds of satellite receivers and other gear they have acquired on their own into Syria in recent months in part because they have not received significant quantities of such equipment from the United States.

The activists’ accounts contrast sharply with assertions by the administration that it has spent millions of dollars and provided about 900 satellite phones and other pieces of equipment to the Syrian opposition.

In Istanbul this month, Secretary of State Hillary Rodham Clinton cited the shipments during a public appearance. “We are providing $25 million in nonlethal aid, mostly communications, to civil society and activists,” she said.

With a major international airport in Istanbul, a 500-mile border with Syria and a supportive government in Ankara, Turkey is a crossroads for supplies flowing to Syrian rebels from Europe and the Middle East. But Syrian activists said they have been frustrated by unfulfilled pledges from U.S. officials that equipment is on its way.

“Our groups have not received anything from the U.S. side,” said Imad Eddin al-Rachid, a former assistant dean at the Islamic Law College in Damascus, who has met with Clinton and other high-level U.S. officials in Turkey in recent months.

More than a dozen Syrians directly involved in smuggling equipment said they have delivered hundreds of devices to groups in Aleppo, Damascus and other beleaguered cities but were unaware of any gear that had been provided by the United States.

Seeking to bolster its support to opposition groups, the State Department recently established a program to provide equipment and instruction to anti-Assad activists. But the program requires participants to travel to Istanbul for training before they are given any gear.

U.S. officials and Syrian nationals involved in the program said that it is slated to expand in the coming months but that fewer than two dozen laptop computers and satellite modem kits had been distributed so far.

U.S. officials acknowledged that the program, known as the Office of Syrian Opposition Support, only started work two months ago and had been hampered by bureaucratic and diplomatic delays. Among them, officials said, was concern by the Turkish government that OSOS could emerge as a rival to other Syrian groups or secretly be used to ship weapons into Syria.

It is “fair to say that it’s very much a work in progress,” said Rick Barton, the assistant secretary of state who oversees the program. “We are moving as aggressively as possible now that we have cleared many of the cobwebs in our own system and with our allies.”

Nonlethal supply chain

In the meantime, Syrian activists said they have assembled elaborate supply chains that account for the bulk of electronics, cash, medical supplies and other material being moved through Turkey by Syrian opposition groups. Activists said separate networks funnel weapons to the rebels.

A key outpost in the nonlethal supply chain is an office in a high-rise near the airport in Istanbul. Inside, activists oversee an informal procurement operation that takes orders from groups inside Syria, buys electronics from suppliers in Britain and has them shipped to Paris, where the devices are packed into suitcases by Syrians flying to Istanbul.

Among the recent arrivals was a pair of Astra 2 satellite receivers earmarked for opposition leaders in Homs and Hasakah. From Istanbul, the gear is carried to the border, often by bus, then picked up by smugglers and activists making regular runs into Syria.

The two devices were all that were left “from a large shipment of 70 units we bought last month,” said a 30-year-old Syrian who asked to be identified by a pseudonym, Abu Lina, citing concern for the security of his family inside Syria.

Every shipment is logged in a ledger that records serial numbers, names of recipients and phone or Skype contact information to confirm deliveries and provide technical support.

The Astra 2 typically comes with a conspicuous satellite dish. But Abu Lina said his group sends only the center “needle” so that it can be slipped into a standard television dish indistinguishable from those that top almost every apartment building in the Middle East.

Satellite connections are no substitute for weapons in a conflict that the United Nations estimates has killed at least 18,000 people and plunged Syria into civil war. But activists said communications gear is nevertheless essential to the survival of opposition groups.

The equipment enables activists to coordinate even during ­government-imposed Internet blackouts, providing warnings to civilians about approaching Syrian troops or sharing locations of makeshift medical facilities.

The gear is also used to document the brutality of the Assad crackdown, as well as broadcast propaganda, including footage recently posted online that purported to show a Syrian military pilot captured after his plane was shot down.

Abu Lina said his group, which gets funding and office space from the umbrella group Syrian National Council, has sent at least 200 satellite receivers and 100 satellite phones into Syria in recent months. Asked how many he had gotten from the United States, he replied: “None whatsoever. Just promises.”

Others provided similar accounts. An activist with ties to opposition elements in the Syrian city of Latakia said his most recent shipment included 50 radio handsets — referred to almost universally among Syrians as “talkie-walkies” — and an 18-foot antenna that, because of its length, had to be delivered to the border by bus.

The money to buy the equipment comes “from donors outside the country,” said the activist, Abdul Rehman Selwaye. He added that neither he nor others in his group had received U.S. gear, saying that American aid “is all virtual.”

U.S. training program

U.S. officials said Syrian opposition groups may be unaware of how much gear came from the United States because it was largely distributed through nongovernmental organizations. The officials also suggested that activists may be unhappy with the amount they have gotten or convinced that rivals have gotten more.

Edgar Vasquez, a State Department spokesman, said the department had “provided more than 900 pieces of nonlethal equipment, mostly communications gear, to civilian activists and opposition groups.”

He declined to elaborate, saying that “given the Syrian regime’s intense and sophisticated efforts to crack down on opposition activity,” doing so could “put people’s lives at risk.”

An initial $10 million in non­lethal aid was provided through the department’s Middle East Partnership Initiative, officials said. An additional $15 million is being administered by the Bureau of Conflict and Stabilization Operations.

The latter includes the recently created OSOS. The program was set up by a British company under a State Department grant and operates out of an office in the tourist-heavy Taksim area of Istanbul. Its staff members include nine Syrian volunteers who are paid stipends and whose living expenses are covered.

OSOS officials defended its training-first approach, citing the need to ensure gear is going to Syrians who know how to use it and saying that they follow security measures designed to protect their signals from serving as targets for Syrian government strikes. The State Department emphasizes that it provides only nonlethal aid.

In a swipe at critics, an OSOS consultant said the office was created to prepare groups for the aftermath of Assad’s expected fall, not merely to funnel material to “armchair activists” in Istanbul.

OSOS has had 18 trainees go through its two-day instructional course on using satellite kits, which include a laptop, a portable satellite receiver and a 50-meter cable to run a connection from a rooftop to a basement or bunker.

“We were taught when we hear jet fighters to turn off the devices,” as well as using code words and encryption, said one of the recent trainees, a 20-year-old student from Aleppo University who asked to be identified as Abeer. Her only complaint was that her package included “only 100 megabytes” of access to satellite service, barely enough to cover a few sessions on Skype, although OSOS officials said she could receive more.

Julie Tate contributed to this report.