* US Central Command says it was warned that adversaries

used location data to target troops

* Lawmakers urge Pentagon to act, citing adtech industry

as national security threat

* Calls for disabling ad IDs, restricting location

sharing, and moving away from Chrome on devices

By Raphael Satter

WASHINGTON, May 28 (Reuters) - U.S. forces deployed to

war zones have been targeted using commercially available

location data, according to reports fielded by military

officials, an illustration of how the global surveillance

economy is shaping the battlefield.

In a letter shared with Reuters by U.S. Senator Ron Wyden, an

Oregon Democrat, U.S. Central Command said it had "received

multiple threat reports concerning adversary exploitation of

commercial location data to target or surveil U.S. personnel in

theater." The message, sent on April 14, offered no further

specifics, but Centcom's area of responsibility includes the

Gulf, where U.S. forces are facing off against the Iranian

military over the Strait of Hormuz.

The disclosure was the first official confirmation that U.S.

forces had been targeted in an active war zone, Wyden and a

bipartisan group of legislators said in a letter sent on

Thursday to the Pentagon.

"Commercial location data can be used to identify where U.S.

troops congregate and their pattern of life, which can be

exploited by adversaries to target attacks such as missiles,

drones, and roadside bombs, as well as for counterintelligence

purposes," the letter warned. Wyden said in a statement that it

was time to "start treating the adtech industry as a national

security threat."

The Pentagon said in an email it would respond directly to

the lawmakers but did not elaborate. The lawmakers said in their

letter that their efforts to obtain more information from

military officials about the reported targeting had been

unsuccessful.

LOCATION DATA TRADE FUELS PRIVACY CONCERNS

Location data is widely used in digital advertising, which

is a key source of revenue for many tech companies. Such data is

typically collected from smartphones or other devices by apps or

service providers before being sold to data brokers who collate

and resell the data, sometimes via complex networks of

intermediaries.

Although the threat to privacy inherent in selling the

details of people's day-to-day movements on the open market has

long been a matter of public discussion, its potential as a

national security risk has recently drawn concern as well.

As far back as 2016, one U.S. defense contractor was able to

leverage commercially available location data to track special

operations forces from their bases in the United States to a

sensitive staging post in Syria, according to an account first

disclosed by the Wall Street Journal.

More recently, journalists at Wired and two German news outlets

drew on billions of coordinates collected by a data broker to

expose the granular comings and goings of people stationed at or

around 11 U.S. military and intelligence sites in Germany.

Two groups that represent digital advertisers, the

Interactive Advertising Bureau and the Association of National

Advertisers, did not return emails seeking comment.

The letter from U.S. lawmakers to the Pentagon said that,

given what military officials know about the trade in location

data, they should have acted faster to protect their personnel,

for example by disabling the unique advertising ID attached to

military-issued devices, automatically turning off location

sharing on smartphones in the field, and steering staff away

from Google's Chrome web browser toward more privacy-focused

alternatives.

One of the letter's cosigners was U.S. Representative Pat

Harrigan, a North Carolina Republican who was formerly a U.S.

Army Special Forces officer. Harrigan said that browsers like

Chrome "are built from the ground up to collect and share user

data" and that every day they remain on government-issued

devices "is another day we are handing our adversaries a weapon

against our own troops."

In a statement, Alphabet's Google said that Chrome had

"industry leading security." The company added that it had "long

advocated for stronger rules and safeguards against data

brokers."