Do you stand at parade rest for a NCO of another military branch?

As MP's at Walter Reed (in D.C.) we would salute police officers of rank - Lieutenants and up. We would address D.C. police officers by rank as well. We CERTAINLY treated ALL military branch NCO's and Officers just like we would Army personnel. No, when stopping any of them for traffic or other violations, while VERY respectful, we did not assume an at-ease or attention position - always used police tactics (stance) which proved appropriate when I nabbed an Army Major for carrying a loaded handgun on base; compounded by no carry permit. Even he was treated with the utmost, though cautious respect, even when placing him in hand irons.

SSG Bill McCoy - jacked up the base commander at Grand Forks ND for getting too close to the WSA. All respect paid to his rank, full Colonel. Yes sir. Thank you sir. You are in the wrong sir.

If you can translate their rank from their insignia. Served with some field grade African Officers that in dress uniform you would have thought they were the General of the entire army instead of LT or CPT. Noticed the same kind of thing with some of the Central America Allied Officers.