Rockwell International, North American Aircraft B-1 Lancer variants 

 B-1A Lancer

The B-1A is a "swing-wing" strategic bomber of blended wing-body design intended for high-speed low-altitude penetration missions.

 B-1B Lancer Variants

The B-1B is a multi-role, long-range bomber, capable of flying intercontinental missions without refueling, then penetrating sophisticated enemy defenses. It can perform a variety of missions, including nuclear strike, cruise missile carrier, conventional weapons carrier, long-range sea surveillance and mine-laying.
Block A: Initial conventional capability was optimized for delivery of Mk-82 non-precision 500lb gravity bombs. All B-1Bs were designated as "Block A" models before the CMUP began.

Block B: Block B gave the B-1B an improved Synthetic Aperture Radar, as well as some upgrades to to the Defensive Countermeasures System, which improved its maintainability and provided a reduced false alarm rate.

Block C: Block C "Enhanced Capability" provided for delivery of up to 30 Cluster Bomb Units (CBUs) per sortie for enhanced conventional capability against advancing armor.

Block D: Block D "Near Precision Capability" gives B-1 aircrews increased abilities to accurately put bombs on target with improved weapons and targeting systems, as well as giving them advanced secure communications capabilities.

Block E: Block E "Standoff Capability" upgrades the current avionics computer suite and integrates Wind Corrected Munitions Dispenser (WCMD), Joint Standoff Weapon (JSOW) and Joint Air to Surface Standoff Missile (JASSM) for standoff capability (FY02). Initially Block E was confined to cComputer and WCMD upgrades and Block F the DSUP integration upgrade, with a Phase III Block G "Standoff Capability" containing the JSOW & JASSM integration upgrades.

Block F: Block F improves the aircraft’s electronic countermeasures’ situational awareness and jamming capabilities.
  The Towed Decoy System (TDS) provides an interim improvement in the survivability of the B-1B in a hostile environment until the Defensive System Upgrade Program is complete.
  The Defensive Systems Upgrade Program (DSUP) is a major modification to the defensive system on the B-1B. It provides improved threat warning to the aircrew and enhances the survivability of the B-1B in a hostile environment. DSUP will replace the current defensive system, the ALQ-161, with the ALR-56M radar warning receiver and the Navy-developed IDECM radio frequency jamming system, which includes a fiber optic towed decoy (FOTD).

Block G: Block G Initially Block E was confined to cComputer and WCMD upgrades and Block F the DSUP integration upgrade, with a Phase III Block G "Standoff Capability" containing the JSOW & JASSM integration upgrades.