New information has emerged about a mortar attack on a U.S. supply base outside Baghdad that claimed the life of one American soldier and left 30 others wounded. A senior Pentagon official has revealed U.S. forces quickly determined the site where Iraqi attackers fired mortars into a coalition logistics base west of Baghdad late Wednesday.

But this official, speaking on condition of anonymity, says commanders declined to order so-called counter-battery fire that could have disrupted the attack and possibly killed the assailants.

The official tells VOA this is because the mortars were fired from a heavily-populated area where any American counter-attack could have caused civilian casualties.

The official says U.S. troops did pursue the attackers. He declines to say whether any of the suspected insurgents involved in the incident were apprehended.

The attack on the logistics base comes at a time when U.S. commanders say the overall number of incidents involving coalition forces throughout Iraq has dropped from about 40 a day in November to fewer than 20 now.

But the senior Pentagon official who spoke to VOA warns insurgent forces in Iraq are constantly adjusting their tactics.

The official says if U.S. commanders do not adjust theirs in response, then coalition troops will remain vulnerable to attacks. The official insists commanders are extremely sensitive to this.

The official's comments coincide with the publication of a Marine Corps document that describes Iraqi insurgent intelligence on American forces, tactics and procedures as "very, very good." The document, written last year, also reveals Iraqi workers hired by the U.S. military have been caught collecting intelligence and placing electronic eavesdropping devices in and around coalition facilities.