Katy Perry trained with Marines before making Part of Me video

Katy Perry trained with service members at a Marine Corps base before shooting her military-themed music video Part Of Me.

The I Kissed a Girl hitmaker, who is currently in the midst of her divorce from actor Russell Brand, shows off her new tough-girl image in the video by donning fatigues, engaging in hand-to-hand combat and marching in formation with other recruits - all while wielding a machine gun.

And Perry reveals she went all out to make the the clip as authentic and gritty as possible by making a trip to California's Camp Pendleton to learn from the best so she could do her own stunts.

She tells MTV News, "I got a fantastic person to work me out and get me into really good shape... On the actual base, I did a lot of things... I know how to carry my weight a little bit more."

However, there was one task Perry just couldn't master - so the director had to work around the scene with clever camera angles.

She continues, "One thing I can't do, and I hope that there are other people out there that feel the same way, is climb a rope. Oh my gosh, it's so hard to climb rope! It's all about grip and arms. I tried five or six times on set, but I had to cheat that shot. My hands were shaking."

And she insists the whole experience has helped her cultivate a new-found respect for servicemen and women.

Perry adds, "This music video, as much as I was sore and exhausted, I was so educated on people in the service who I've always respected, but this time the respect goes beyond and above anything I could've imagined. The stuff that they go through, the loyalties and strengths that they all possess, it seems like they are seriously, not to sound weird, like the heart of America. I was meeting kids that were 17, 18... and they just all had their own stories... So it was really interesting."