The base, leased to the United States by Britain, is one of its key military facilities in the Asia-Pacific region, and was used as a hub for long-range bombers and ships during the wars in Afghanistan and Iraq.
The four B52H Stratofortresses, which can carry nuclear weapons or other precision-guided munitions, were spotted on a southern tarmac at Diego Garcia on Monday at 0922 GMT.
Images provided by Planet Labs indicate they arrived in mid-May.
A C-17 Globemaster III troop and cargo transport plane is also at the base, according to the AFP analysis, as well as six jets likely to be KC-135 airborne refuelling tanker.
The Pentagon said Monday that it was sending “additional capabilities” to the Middle East amid an escalation of the Iran-Israel conflict, while the aircraft carrier USS Nimitz cancelled a Vietnam visit to head toward the Indian Ocean according to Marine Traffic, a ship-tracking site.Washington has also redeployed around 30 refuelling planes toward bases in Europe.
