By Guto Harri
BBC North America Business correspondent
Security concerns have been prompted in the US by the takeover of a second British firm by a Dubai-based company.
Doncasters Group makes parts for defence contractors like Boeing
The Doncasters Group, which has nine US facilities manufacturing precision parts for defence contractors, is being bought by Dubai International Capital.
The news follows a fierce political row sparked by the takeover of P&O's operations at six American ports by a company from the United Arab Emirates.
An Israeli firm is also being investigated by US congressmen.
The US Congress is not usually told about - and has not generally been interested in - ongoing investigations by the committee on foreign investment.
But in the wake of the unresolved row over the Dubai Ports World deal, the committee, it seems, has decided now to keep Congress better informed of other investigations.
The London-based Doncasters Group makes precision parts for major defence contractors like Boeing, Honeywell and General Electric.
The parts are used in military aircraft and tanks.
Dubai International Capital wants to buy the firm for $1.2bn (£690m), but the investigation only began this week.
Checks on an Israeli firm apparently began earlier this month, before the recent controversy.
The firm in question, Checkpoint Software Technologies, is trying to take over Sourcefire, a Maryland-based software security firm which supplies the US defence department.
Concerns apparently centre on the possibility of sensitive technology being passed on to other countries.