Yes and no. The active duty military is restricted by something called Posse Comitatus, which basically says that active duty forces can't be used on US soil. The National Guard doesn't come under that act, because each state's Guard is under the command of the state governor.
“The active duty military is restricted by something called Posse Comitatus”
Hate to break it to you, but Posse Comitatus is effectively repealed.
These changes were included in the John Warner National Defense Authorization Act for Fiscal Year 2007 (H.R. 5122), which was signed into law on Oct 17, 2006, subsequently repealed Posse Comitatus in their entirety.
Section 1076 is titled “Use of the Armed Forces in major public emergencies”. It provided that: “The President may employ the armed forces... to... restore public order and enforce the laws of the United States when, as a result of a natural disaster, epidemic, or other serious public health emergency, terrorist attack or incident, or other condition... the President determines that... domestic violence has occurred to such an extent that the constituted authorities of the State or possession are incapable of maintaining public order... or [to] suppress, in a State, any insurrection, domestic violence, unlawful combination, or conspiracy if such... a condition... so hinders the execution of the laws... that any part or class of its people is deprived of a right, privilege, immunity, or protection named in the Constitution and secured by law... or opposes or obstructs the execution of the laws of the United States or impedes the course of justice under those laws.”
Doesnt it say for law enforcement? It doesnt say they cant be used, IIRC.