Moscow is crossing 'the United States' red line' through stationing its nuclear capable long-range bombers in Cuba, a US general says.

"If they did I think we should stand strong and indicate that is something that crosses a threshold, crosses a red line for the United States of America," said General Norton Schwartz, nominated to be the air force's chief of staff.

His remarks were made after Russian newspaper, Izvestia, quoted an unnamed senior Russian air force official that the military is thinking of flying long-range bombers to Cuba.

It was unclear if Moscow would reopen a base in Cuba or merely use an airfield there for stopovers by the bombers, Tu-160s and Tu-95s, which are already capable of reaching the United States from bases in Russia.

The move is considered as a response to Washington's plans for stationing the components of a missile defense shield system in Eastern Europe.

Russia has formerly vowed to take retaliatory measures against the United States if Washington goes ahead with the project.

SB/DA