The SBIRS satellites are slated to replace the existing DSP satellites that detect missile launches from around the world, but unfortunately the satellites have had problems but the program is moving ahead:

The Space Based Infrared System (SBIRS)-High satellite program is a key component of the USA’s future missile alert system, designed to give maximum warning and monitoring of ballistic missile launches anywhere in the world. The new satellites will replace the existing Defense Support Program (DSP) fleet. Their infared sensors have 2 times the revisit rate and 3 times the sensitivity of DSP, while providing better persistent coverage.

Unfortunately, the program has been beset by massive cost overruns, technical challenges that continue to present problems, and uncertain performance. Despite its problems, the U.S. Air Force is proceeding with the program, even as it examines potential alternatives and supplements.  [Defense Industry Daily]

There is whole lot more good info about SBIRS at the link.