The Justice Department wrote to the FCC on Monday asking the agency to delay any action regarding Softbank's merger with Sprint until DOJ, the FBI, and the Department of Homeland Security can complete their review of any national security, law enforcement, or public safety concerns. The two companies agreed to a $20.1 billion deal in October that would give the Japanese firm a 70 percent stake in Sprint. The Justice Department's request doesn't indicate that it has found any significant concerns regarding the transaction at this time.

AT&T has raised concerns about the prospect of Softbank purchasing Sprint, previously releasing a carefully-worded about Japan's largest wireless company controlling more spectrum in the U.S. market than any other carrier. The statement could have been an attempt to drum up security concerns similar to those that have prevented the Chinese telecom provider Huawei from making bigger inroads into the U.S. market. However, Huawei has generated significant concern because of alleged ties between the company and the Chinese Peoples Liberation Army, and not merely because it is a foreign firm. Foreign ownership of major wireless carriers is not uncommon in the U.S.: the nation's fourth-largest wireless carrier, T-Mobile USA, is a subsidiary of the Germany's Deutsche Telekom, and UK's Vodafone owns a significant stake in Verizon Wireless, the nation's largest wireless carrier. AT&T and Sprint have also locked horns previously after Sprint expended significant time and resources pushing the government to block AT&T's failed acquisition of T-Mobile USA.