Israeli military and intelligence officers claim that Hezbollah seized the M113s from the Lebanese Armed Forces (LAF) who received them from the US, but Washington rejects any such involvement.

— Tobias Schneider (@tobiaschneider) November 13, 2016

​Last month, an Israeli intelligence agent recognized that "these specific APCs" are identical to vehicles the US gave Lebanon, according to the Times of Israel. This is not just an "assumption," but something "we know," a senior Israeli defense official said. Israel is a key US ally in the region, complicating the dispute.

For its part, the US State Department adamantly denies that the APCs could have been sourced from the LAF, citing Lebanon’s "exemplary" end-use compliance history, according to spokesman John Kirby. The Pentagon noted that several M113s have "likely been in Hezbollah’s inventory for a number of years" and that the M113s are "common" in the area, per Defense News.

The DoD’s November structural analysis concluded that the troop carriers were not from the LAF, and the DoD has not changed positions since that analysis, according to a spokesman.

— Tobias Schneider (@tobiaschneider) November 13, 2016

​In private discussion US defense officers pointed out that Hezbollah’s APCs in Syria are aging, Defense News adds. As such, there are a couple possibilities that answer where the contested vehicles originated. In 2000, Hezbollah overran zones in southern Lebanon and seized a slew of military vehicles from the Southern Lebanese Army (SLA). They also could have come from Iran, Hezbollah’s strongest supporter.

Defense analyst Tobias Scheider told Sputnik News "the most likely theory is that these were spoils of the 2000 SLA withdrawals, possibly added by one or two vehicles procured from old private war stocks." Due to LAF's "diligent" and "transparent" internal accounting systems, US officials have showered "praise" on LAF's ability to track supplies received from the US. Further, Schneider adds that since 2005, "there is no recorded example of deliberate transfer of US-supplied arms from the Lebanese Army to Hezbollah or to anyone else." The APCs have floated through the region so much in recent decades "it can be daunting to establish the precise chain of custody of any given vehicle that may have been captured during those years."