The withdrawal of troops from Afghanistan is costing a British telecoms company $1m (£600,000) a month.
The chief executive of Inmarsat, a FTSE 100 company that provides satellite communications to soldiers, said revenue from military operations in Afghanistan had fallen by about $10m to $15m a year.
"We are down about $1m a month," Andrew Sukawaty, Inmarsat's chairman and CEO, said on Thursday. "Afghanistan represents $20m-$30m of revenues and some piece of it just went away." During the height of the conflict, Inmarsat made "in excess of $35m" from Afghanistan.
Sukawaty said the beginning of the withdrawal of some of the 130,000-strong International Security Assistance Force (Isaf) and a decline in active operations in the country had led to decreased demand for its services.
"When troops sit there we get less business," he said. "When they move around, we get more business."
However, Inmarsat said it expected to continue to make money from Afghanistan for a long time after the December 2014 deadline for withdrawal of all US, UK and Nato troops. About 10,000 US troops are due to pull out by the end of 2011, followed by another 23,000 by next summer.
Inmarsat also makes money by providing communications to unmanned observational military drones, as well as the media and aid organisations active in the Middle East and north Africa.
Shares in Inmarsat fell by 20% to 380p by 12.30pm on Thursday after the company abandoned its growth targets for its key maritime division.
Inmarsat said it would continue to be "adversely impacted" by its customers upgrading to its broadband services rather than sticking with older calls-only terminals. The broadband terminals make less money because sailors can use cheaper internet-based phone services such as Skype rather than make expensive satellite calls.
The company said it remained confident in its long-term plan to switch to broadband terminals, but warned there was a risk of some of its customers switching to competitors.
Commenting on the drop in the share price, which wiped $350m off the company's market value, Sukawaty said: "If people think this is an ex-growth company, they're wrong."
Mark James, an analyst at Liberum Capital, agreed. He said: "We remain of the view that the current level materially undervalues both the core business [Liberum estimates $7 a share] and the US spectrum [which the company has recently entered into deal with an American wireless broadband provider]."