NEW YORK -- The US Department of the Treasury on Tuesday put 27 Iranian airlines on its Specially Designated Nationals List thus targeting all remaining Iranian airlines in a bid to step up pressure on Iran.

The department said in a press release that "Iran's commercial airlines have long supported the Iranian regime's destabilizing activities," with the Islamic Revolutionary Guard Corps using ostensibly private airlines for the procurement and transport of weapons and the ferrying of personnel.

The United States first sanctioned Iranian airline Mahan Air in October 2011, and targeted multiple companies seen as general sales agents of Mahan Air on July 30.

The sanctions also targeted "covert front companies, foreign intermediaries, and deceptive transshipment routes that Iran relies on to obtain US-origin aircraft and sensitive technology," according to the release.

In particular, the Treasury Department's Office of Foreign Assets Control (OFAC) designated four companies from Türkiye, Malaysia and Kazakhstan on the grounds of acting as Mahan Air's cargo service providers and general sales agents.