The U.S. State Department is airlifting armored vehicles and other equipment to its missions in Sudan, part of efforts to boost security in the wake of last week's attacks on diplomatic compounds in North Africa and the Middle East. A giant cargo plane operated by Russia'sVolga-Dnepr Airlines LLC took off from Washington, D.C., with the equipment early Wednesday en route to Tunis, and was due to continue to Khartoum.

The shipment was revealed in regulatory filings after a U.S. cargo airline objected to the State Department's hiring of the Russian carrier, which must secure special permission to carry outsize cargos on its huge Antonov AN-124 planes on missions for the U.S. government and private clients in the U.S.

Volga-Dnepr, backed by the State Department, argued in its request for flight clearance from the Department of Transportation that only its planes were suitable for the 52.5-ton shipment that included seven armored vehicles and other "physical security equipment," according to filings.

Colon Miller, the military operations manager for Volga-Dnepr's U.S. arm, confirmed the flight was en route to Tunis with the equipment after it secured clearance from the Transportation Department.

Ypsilanti, Mich.-based Kalitta Air LLC had tried to block the use of Volga-Dnepr, arguing in filings that its own Boeing Co. (BA) 747-200 planes could carry the equipment and unload them in the two African capitals.

Kalitta was the only carrier to object to the request. The company said it had no comment beyond the regulatory filings.

The State Department didn't immediately respond to a request for comment.

Embassy security is being stepped up after last week's deadly attack that killed the U.S. ambassador to Libya and three other staff members in Benghazi, as well as the assaults on compounds in Tunisia, Sudan and Yemen.

The U.S. said during the weekend it would withdraw all nonessential embassy staff in Sudan, and issued travel warnings to American citizens following attacks on its missions in the two countries.

Write to Doug Cameron at doug.cameron@dowjones.com

Corrections & Amplifications

This item was corrected at 6:03 p.m. EDT to show that armored vehicles were being airlifted to Sudan, and nonessential embassy staff would be withdrawn from Sudan. The original incorrectly stated that armored vehicles were being airlifted to Somalia, and in the last paragraph that nonessential embassy staff would be withdrawn from Somalia.