SAN FRANCISCO, July 18 (Reuters) - A U.S. senator is

asking the Pentagon for more information on Microsoft's ( MSFT )

reported use of Chinese engineers in maintaining military cloud

computing systems, according to a copy of the letter seen by

Reuters.

Senator Tom Cotton, an Arkansas Republican who chairs the

chamber's intelligence committee and also serves on its armed

services committee, sent the letter to Defense Secretary Pete

Hegseth after a report in investigative journalism publication

ProPublica earlier this week. The report detailed Microsoft's ( MSFT )

use of Chinese engineers to work on U.S. military computing

systems under the supervision of U.S. "digital escorts" hired

through subcontractors who have security clearances but often

lacked the technical skills to assess whether the work of the

Chinese engineers posed a cybersecurity threat.

Contacted by Reuters about both the ProPublica report and

Cotton's letter, Microsoft ( MSFT ) declined to comment. The company,

which is a major contractor to the U.S. government and whose

systems have been breached by both Chinese and Russian hackers,

told ProPublica that it disclosed its practices to the U.S.

government during an authorization process.

The Defense Department did not immediately respond to a

request for comment.

Cotton asked the U.S. military for a list of all contractors

that use Chinese personnel and for more information on how U.S.

"digital escorts" are trained to detect suspicious activity.

"The U.S. government recognizes that China's cyber

capabilities pose one of the most aggressive and dangerous

threats to the United States, as evidenced by infiltration of

our critical infrastructure, telecommunications networks, and

supply chains," Cotton wrote in the letter. The U.S. military

"must guard against all potential threats within its supply

chain, including those from subcontractors."