ISIL fighters likely seized at least one cache of weapons airdropped by the U.S. after it missed its intended recipients, besieged Kurdish militias defending the Syrian border town of Kobane, a Pentagon spokesman said Wednesday.

"Yesterday we announced that one resupply bundle went astray and was destroyed," said Army Col. Steve Warren. "We have since relooked at that and we have determined that a second bundle also went astray and probably fell into enemy hands."

The load, which includes hand grenades, ammunition and rocket-propelled grenade launchers, was shown in a video uploaded by a media group loyal to the Islamic State in Iraq and the Levant (ISIL).

The video appeared authentic, according to the London-based Syrian Observatory for Human Rights, which bases its information on a network of activists on the ground. U.S. authorities on Tuesday said they were looking into the possibility of one bundle of arms being lost to the extremists but added that the majority of shipments had gone to the right people.

On Sunday the Pentagon announced it had begun dropping weapons provided by Iraqi Kurds to Kurdish fighters in Kobane, which lies near the Turkish border. ISIL has been trying to seize the Kurdish enclave for over a month now, causing the exodus of some 200,000 people from the area into Turkey. While Kurds are battling on the ground, the U.S.-led coalition against ISIL has been targeting them from the air.

“We’re still taking a look at [the video] and assessing the validity of it. So I honestly don’t know if that was one of the [loads] dropped,” Pentagon spokesman Rear Adm. John Kirby told reporters on Monday.

He said it was “not out of the realm of the possible” that a bundle had fallen into ISIL’s hands but added that he was confident that the “vast majority” had reached the intended targets.

On Tuesday ISIL loyalists on social media posted sarcastic thank you notes to the United States, including one that read “Team USA.”

But the lost weapons drop was more an embarrassment than a strategic loss. ISIL fighters already possess millions of dollars’ worth of U.S. weaponry that they captured from fleeing Iraqi soldiers when the group seized swaths of Iraq in June.

On Tuesday the U.S. Central Command said U.S. military forces conducted four airstrikes near Kobane that destroyed ISIL fighting positions and several buildings that the group had taken over.

Also Tuesday, Syrian government airstrikes hit a rebel-held town along the country's southern border with Jordan, killing at least eight people. Activists with the Local Coordination Committees (LCC) and the Observatory said the number of those killed was likely to rise as more victims under the rubble are found.

The LCC said Syrian government planes dropped crude explosives-laden canisters on the town of Nasib on the Syria-Jordan border. The airstrikes are part of battles between Syrian government forces and rebel groups not associated with ISIL for control of the area.

Syrian government forces have been heavily bombing rebel areas in recent weeks, while the U.S-led coalition has been conducting airstrikes against ISIL elsewhere in Syria.

Al Jazeera and wire services