Toyota, the world’s second largest vehicle manufacturer, has said it is assisting a United States investigation into how the Islamic State terrorist organization (also known as ISIS) acquired the large number of Toyota pick-up trucks and SUVs that appear in its propaganda videos, according to a report by ABC News.

The investigation, which is being led by the Terror Financing unit of the U.S. Treasury Department, is part of an effort to prevent Western-made goods from ending up in the hands of the terror group.

Toyota maintains that it does not know how ISIS obtained the vehicles. “We briefed Treasury on Toyota’s supply chains in the Middle East and the procedures that Toyota has in place to protect supply chain integrity,” said Ed Lewis, Toyota’s Washington-based director of public policy and communications.

He added that Toyota has a “strict policy to not sell vehicles to potential purchasers who may use or modify them for paramilitary or terrorist activities.” But it is impossible for the company to track vehicles that have been stolen, or have been bought and re-sold by middlemen, he added.

Toyota Hilux pick-ups and Land Cruisers armed with heavy weapons have featured prominently in propaganda videos shot in Syria, Iraq and Libya.

Lukman Faily, the Iraqi ambassador to the U.S., told ABC News that in addition to re-purposing older trucks, his government believes ISIS has acquired “hundreds” of “brand new” Toyotas in recent years.

“Regrettably, the Toyota Land Cruiser and Hilux have effectively become almost part of the ISIS brand,” said Mark Wallace, a former U.S. ambassador to the United Nations, who is CEO of the Counter Extremism Project, a non-profit working to expose the financial support networks of terror groups.

Toyota’s own figures show sales of Hilux and Land Cruisers tripling from 6,000 sold in Iraq in 2011 to 18,000 sold in 2013, before sales dropped back to 13,000 in 2014.

Toyota said in a statement that it was not aware of any dealership selling to the terror group but “would immediately” take action if it did, including termination of the distribution agreement.

U.S. Treasury officials told ABC News they could not comment publicly about the agency’s engagement with specific private companies. But in response to questions about Toyota, the officials said investigators are “working closely with foreign counterparts and stakeholders” on the issue.