Updated 5:35 pm

At least one bundle of U.S. weapons airdropped in Syria appears to have fallen into the hands of ISIS, a dangerous misfire in the American mission to speed aid to Kurdish forces making their stand in Kobani.

An ISIS-associated YouTube account posted a new video online Tuesday entitled, “Weapons and munitions dropped by American planes and landed in the areas controlled by the Islamic State in Kobani.” The video was also posted on the Twitter account of “a3maq news,” which acts as an unofficial media arm of ISIS. The outfit has previously posted videos of ISIS fighters firing American made Howitzer cannons and seizing marijuana fields in Syria.

ISIS had broadly advertised its acquisition of a broad range of U.S.-made weapons during its rampage across Iraq. ISIS videos have showed its fighters driving U.S. tanks, MRAPs, Humvees. There are unconfirmed reports ISIS has stolen three fighter planes from Iraqi bases it conquered.

The authenticity of this latest video could not be independently confirmed, but the ISIS fighters in the video are in possession of a rich bounty of American hand grenades, rounds for small rockets, and other supplies that they will surely turn around and use on the Kurdish forces they are fighting in and around the Turkish border city.

On Monday, White House Deputy National Security Advisor Ben Rhodes said the U.S. government was confident that the emergency airdropped supplies for the Kurdish forces near Kobani were falling into the right hands.

“We feel very confident that, when we air drop support as we did into Kobani… we’ve been able to hit the target in terms of reaching the people we want to reach,” Rhodes told CNN. “What I can assure people is that, when we are delivering aid now, we focus it on the people we want to receive that assistance. Those are civilians in need. Those are forces that we’re aligned with in the fight against ISIL [the government’s preferred acronym for ISIS], and we take precautions to make sure that it’s not falling into the wrong hands.”

Rhodes was responding to questions about a Monday report in The Daily Beast that U.S. humanitarian aid was flowing into ISIS controlled areas near Kobani by truck. That aid was mostly food and medical supplies, not the kind of lethal weapons in the new ISIS video.

Senior administration officials said Sunday that three American planes dropped a total of 27 bundles near Kobani and more U.S. air drops could come as part of the joint U.S.-Iraqi effort to aid Kurdish fighters in the Kobani area. The supplies were provided by Kurdish authorities, the official said. There have also been at least 135 air strikes against ISIS in the area, according to the State Department.

In the new footage, many of the weapons appear to be U.S. made. But at least one American logistics specialist has his doubts about the authenticity of the video's claims.

“I’ve watched the video several times and it appears bogus to me,” e-mailed Dakota Wood, a former U.S. Central Command logistics planner, now with the Heritage Foundation. “The RPG [[rocket propelled grenade] rounds seem packaged properly, but the final box opened has Spanish markings. The canister opened at the end of the video is not representative of a current U.S. grenade (all our frag grenades are baseball shaped). The photo of M-16s is highly questionable, as the packaging shown is what one would see at a civilian gun show, instead of the packaging I'm familiar with from shipments to armories. Plus, those boxes also don't fit with the air drop bundle shown.”

Wood added, “Why deliver a box of loose grenades all tumbling around knowing it's going to be dropped from x-1000 feet? Why brand new M16s in cardboard boxes that are displayed on tables in a camo-netted setting when the drop occurred in the middle of some pretty sparse terrain and the video/pictures are shared so soon after the drop? There are just a lot of odd elements. And we know from so much propaganda video from all sides that folks will put together and post just about anything to puff-up their story.”

The airstrikes and air drops appear to be having an impact. The Daily Beast’s Jamie Dettmer, reporting from the Syrian border, said the morale in Kobani has shifted in the last 24 hours. But ISIS continues to hold major swaths of territory in and around Kobani, despite widespread media reports to the contrary. And the civilians there are suffering, badly.

“I think what this represents is the President recognizes this is going to be a long-term campaign against ISIL; and that we need to look for whatever opportunity we can find to degrade that enemy and to support those who are fighting against ISIL on the ground,” a senior administration official told reporters.

-- with additional reporting by Noah Shachtman