Securing the Cities Improvement ActThis bill makes changes to the Department of Homeland Security (DHS) Countering Weapons of Mass Destruction Office's (CWMD's) Securing the Cities program, which seeks to detect nuclear or radiological materials to prevent terrorist attacks and other events posing a risk to cities in the United States.Specifically, the bill requires the CWMD to establish performance metrics and milestones for the program and to track performance against them.Also, under current law, in carrying out the Securing the Cities program, the CWMD may only partner with cities that are high-risk urban areas, which are designated by the Federal Emergency Management Agency under a different program. Instead, the bill requires the CWMD to designate the jurisdictions it may partner with for the program, and the designations must be based on the capability and capacity of the jurisdiction relating to preparedness and response, as well as the relative threat to, vulnerability of, and consequences for, such jurisdiction regarding terrorist attacks and other high-consequence events utilizing nuclear or radiological materials.Additionally, within two years of enactment of the bill, the CWMD must submit a report to Congress regarding participation in the Securing the Cities program, the establishment of metrics and milestones, performance against such metrics and milestones, and plans for any changes to the program.