NTT DoCoMo Inc. is ready to return to investing in phone companies outside Asia after rival Softbank Corp.'s deal to acquire a majority stake in Sprint Nextel Corp. in the U.S., its chief executive officer said.

"The acquisition plan of Sprint was quite astonishing for us," Kaoru Kato, 61, said in an interview Monday at the Mobile World Congress in Barcelona. "I hope this will lead to success for the U.S. market and for Softbank as well, but the hurdle will be very high."

DoCoMo has scaled back bets on non-Asian phone companies after earlier investments in Royal KPN NV and the company then known as AT&T Wireless Services Inc. led to writedowns a decade ago.