Russia would cross "a red line for the United States of America" if it were to base nuclear capable bombers in Cuba, a top US air force officer warned on Tuesday.
"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.
He was referring to a Russian news report that said the military is thinking of flying long-range bombers to Cuba on a regular basis.
It was unclear from the report whether that would involve permanent basing of nuclear bombers in Cuba, or just use of the island as a refueling stop.
In his confirmation hearing to become the air force's chief of staff, Schwartz was asked what he would recommend if Russia were to base nuclear capable bombers in Cuba.
"I would certainly offer the best military advice that we engage the Russians not to pursue that approach," he said.
The newspaper Iszvestia on Monday cited an unnamed senior Russian air force official in Moscow as saying that Russia may start regular flights by long-range bombers to Cuba in response to US plans to install a missile defense system in eastern Europe.
A White House spokeswoman declined to comment on the Russian report because there had been no "official response from the Russian government."
Conducting long-range bomber patrol to Cuba would signal a reawakening of military cooperation by former Cold War allies Moscow and Havana, and recall the 1962 missile crisis that brought Washington and Moscow to the brink of war.
Over the past year, Russia already has revived long-range strategic bomber patrols in the Pacific and north Atlantic.
The Russian moves come amid rising tensions over the US missile defense plans, and warnings by Moscow that it will be forced them to counter them militarily.
Until now, US officials have shrugged off the stepped up Russian military activity, while insisting that a radar in the Czech Republic and 10 missile interceptors it plans to install in Poland pose no threat to Russia.
White House press secretary Dana Perino recalled assurances US President George W. Bush offered Russian President Dmitry Medvedev two weeks ago at a G8 summit.
"The president repeated that our missile defense system should not be seen as a threat to Russia, we want to actually work with the Russians to design a system that Russia, and Europe and the United States could work on together as equal partners and we'll continue to do that," she said.
"We seek strategic cooperation with the Russians. We want to work with them on preventing missiles from rogue nations like Iran from threatening our friends and allies," said Perino.
But Medvedev has warned that the missile defense project worsens regional security and will force Moscow to consider counter-measures.