A top State Department official on Thursday said that bombing oil pipelines controlled by Islamic State (or ISIS) in Syria is now a "viable option" under consideration by the U.S. military.

Julieta Valls Noyes, the US deputy assistant secretary for European and Eurasian Affairs, was in London and her comments were first reported by the British press. Citing figures that estimate ISIS is generating nearly $2 million every day by selling crude oil reserves it now controls, Noyes said that the U.S. may expand targeting of oil-related infrastructure inside Syria to include "kinetic strikes against some of the pipelines" and other "physical action to stop the flow."

According to the Independent, Noyes said that sale of fuel is one of the U.S. government's "principal concerns" regarding ISIS' ability to fund its ongoing military operations and that in addition to other methods to stem the group's the sale of oil "air strikes are a viable option."