The U.S. Government recognizes the value of short-term academic exchanges and permits international scholars entering the U.S. in "business" or "tourist" visa classifications to receive payment of honoraria for "usual academic activities". Reimbursement for travel and reasonable incidental expenses, such as accommodations and meals, are also permitted under the same conditions.
While academic institutions may pay honoraria and/or to provide reimbursement of expenses to foreign nationals who enter the U.S. as tourists (B-2/VWT) or visitors for business (B-1/VWB), there are certain conditions for payment. Not everyone in B-1/B-2 or VWB/VWT is eligible.