Officials at Afghanistan's finance ministry didn't respond to requests to comment on the Sigar audit.

WSJ: Kabul's Tax Levies Raise Flags From U.S. Watchdog

" The Sigar audit, the official added, "does not carefully distinguish between taxable and tax-exempt contracts.

WSJ: Kabul's Tax Levies Raise Flags From U.S. Watchdog

"At least nine of the contractors we interviewed had shipments of goods critical to U.S. and coalition operations delayed as a result of unresolved tax assessments, " the Sigar audit said.

WSJ: Kabul's Tax Levies Raise Flags From U.S. Watchdog