The Department of Justice sued Thursday to block the $14 billion Hewlett Packard Enterprise Company acquisition of wireless tech competitor Juniper Networks.

The Justice Department on Thursday sued to block the tie-up, a $14 billion deal that would join the second- and third-largest companies providing wireless networking solutions for large corporate customers.

DOJ cited reduced competition in the wireless market as the biggest problem with the proposed $14 billion sale of Juniper Networks to Hewlett Packard Enterprise. The vendors say they plan to “vigorously defend the transaction in court.