Congressional security officials are instituting "heightened security measures" at the U.S. Capitol due to the escalating conflict in Iran, according to a notice to House offices obtained by Axios.Why it matters: It is a signal of how seriously domestic law enforcement is taking the possibility of attacks on U.S. soil."The Office of the Sergeant at Arms (SAA) is working closely with ... our other law enforcement and intelligence partners to monitor the ongoing conflicts in the Middle East," Hous...