Militants launched another IRAM attack against a joint U.S.-Iraqi compound in the southern Iraqi city of Amarah, near the Iranian border, according to the U.S. military. No one was injured.

A couple weeks ago, I wrote a story about the reappearance of the IRAM, or Improvised Rocket-Assisted Munition, a rarely used weapon that U.S. intellligence officials say is connected to Iran.

Sometimes called "flying IEDs," IRAMs are a potentially deadlier incarnation of the garden-variety IEDs in Iraq and Afghanistan — they're short-range projectiles that catapult toward unsuspecting targets.

In the latest incident, militants on Saturday launched three IRAMs toward Camp Sparrowhawk, a joint Iraqi-American base in Amarah, according to a U.S. military statement with few details of the attack. Most IRAM information is classified as the U.S. military studies the device's components and origins.

There were no casualties and no major equipment damage. Lucky for them, because if you want to know what an IRAM can do, just listen to this American soldier who survived one and was awarded the Purple Heart.

His full account is included in my IRAM story from last month, which you can read here.

"I'd never heard of it — not before it blew up on us," said Spc. Robert B. Walsh, 27, of Venice, Fla., who survived an IRAM blast last summer at the same place as the latest attack.

Walsh, who's still in Iraq, said he was on duty in a guard tower on the American side of the joint outpost at 6 a.m. last June 30, which was supposed to have been a day of celebration as the new U.S.-Iraqi security pact took effect.

Walsh said his only clue before the blast was "a poof sound." In the seconds before impact, Walsh used his radio to alert other soldiers to possible incoming fire.

The IRAM zipped over the wall "like a big bottle rocket," Walsh said. It passed his guard tower and blew up next to a kitchen and barracks where American troops were sleeping.

Two other Purple Heart recipients suffered shrapnel wounds when windows and doors blew into their quarters, cutting their faces and hands. Several vehicles were damaged or destroyed, and the force of the explosion cracked the foundation and shifted the roof of the concrete building.

"It threw me about three or four feet and knocked me unconscious," Walsh said. "When I woke up, everything was on fire and there was debris all over the ground. It left a hole with a 15-foot radius, and it was 4 1/2 feet deep."