WASHINGTON — Russia asked the Obama administration for permission on Monday to fly surveillance planes equipped with high-powered digital cameras over the United States, fueling a long-simmering debate among Pentagon and intelligence officials over Russia's intentions to use such flights to spy on American power plants, communications networks and other critical infrastructure.
Russia has for years conducted unarmed observation flights over the United States — as the United States does over Russia — as part of the Open Skies Treaty that was signed in 1992 by both nations and 32 other countries at the end of the Cold War. Although the treaty and the flights, unfamiliar to most Americans, amount to officially sanctioned spying, their goal has been to foster transparency about military activity and to help monitor arms control agreements.
Now some senior American intelligence and military officials say the new digital technology combined with shifting Russian flight plans would violate the spirit of the treaty. Some Republicans also expressed alarm.
"I cannot see why the United States would allow Russia to fly a surveillance plane with an advanced sensor over the United States to collect intelligence," U.S. Rep. Mac Thornberry, R-Texas, who heads the House Armed Services Committee, said in a statement Monday.
American intelligence officials say Russia's spy satellite network is frayed, so the flights over the United States are a relatively cheap way for Moscow to fill in some important intelligence gaps. That was not so alarming when the Russian flights mainly flew over American missile silos, bunkers and bomber fields, as permitted in the treaty.
In the past few years, however, the Russians flights have developed a wandering eye, critics say, and now fly more routinely over some of the country's most important infrastructure, according to classified military intelligence assessments. (The United States relies on its own powerful satellites, rather than these flights, for such intelligence.)
The U.S. State Department sees the Russian proposal as a small concession that could help preserve the Open Skies Treaty, which is important to European allies, and avoid adding strain to the United States' troubled relationship with Russia.
Allowing Russia to switch to the new electro-optical sensors for these more intrusive flights would give Moscow a more reliable means of conducting surveillance (and an easier way of concealing their objectives) than the clunky, 1960s-era wet-film processing that most nations, including the United States, are transitioning away from, critics said.
Both methods capture the same level of resolution allowed under the treaty. But some senior American military and intelligence officials say the change could leave the United States' most important infrastructure vulnerable to targeting by new long-range Russian cruise missiles.
The Associated Press first reported Russia's request to put the sensors on longer-range Tu-154 aircraft that Russia flies in the United States.
The Russian request comes at a time when Moscow has steadily increased restrictions on where American treaty surveillance planes can fly over Russia, according to the State Department's most recent arms control compliance reports. The Russian restrictions have added to what is already one of the most tense periods in U.S.-Russian relations since the end of the Cold War, with the two nations in strong disagreement over Russian activity in Syria and Ukraine.
The administration must decide in the next four months whether to object to the Russian request that is now before the Open Skies Consultative Commission in Vienna.
"The treaty has become a critical component of Russia's intelligence collection capability directed at the United States," Adm. Cecil D. Haney, commander of the U.S. Strategic Command, wrote in a letter in April to U.S. Rep. Mike Rogers, R-Ala., who heads the House Armed Services subcommittee on strategic forces.
"In addition to overflying military installations, Russian Open Skies flights can overfly and collect on DoD and national security or national critical infrastructure," Haney wrote, referring to the Department of Defense. "The vulnerabilities exposed by exploitation of this data and costs of mitigation are increasingly difficult to characterize."
In the United States, a typical Russian Open Skies flight covers 2,500 to 3,000 miles over two days. There are always seven to 10 American personnel from the Pentagon's Defense Threat Reduction Agency on the Russian plane to ensure compliance.
In addition, the visiting country and the host nation must agree on a flight plan before a mission proceeds. The host nation may propose changes to it.
"All inspected parties are notified ahead of time of the flight path of observation flights, and are able to provide ample warning to sensitive locations within the flight path," Rose E. Gottemoeller, the undersecretary of state for arms control and international security, said in a statement. "Nothing in the treaty precludes shrouding these types of sensitive facilities or activities. Further, the United States receives a copy of every photo taken of flights over its territory, so we have a crystal clear idea of what countries are observing."
The Russians have been using the new electro-optical sensors on shorter-range flights in Europe for the past year, a change approved by European and American officials. In return, Europeans say their Open Skies flights over Ukraine and western Russia since February 2014 have provided them with vital information during Russia's aggression in Ukraine.
Still, military and intelligence officials express serious concern.
"The Open Skies construct was designed for a different era," Lt. Gen. Vincent Stewart, director of the Defense Intelligence Agency, told lawmakers when asked about the Russian flights at a congressional hearing last February, a position his spokesman said he maintains. "I'm very concerned about how it's applied today."
Robert Work, the deputy secretary of defense, told Congress in a letter last June: "Russia's recent activities in a range of areas raise questions about its willingness to abide in good faith with its international commitments, including its obligations under the Open Skies Treaty."
According to the State Department's arms control compliance report in 2015, Russia placed altitude limitations on American Open Skies flights over Chechnya, certain areas around Moscow, and along the border of Russia with the Georgian regions of South Ossetia and Abkhazia. In 2014, Russia imposed flight restrictions over the heavily militarized Kaliningrad.
Russia conducted five flights over the United States in 2014 and four in 2015, according to the Defense Department. This year, Russia is expected to conduct six flights, starting from either Dulles International Airport outside Washington, or Travis Air Force Base in California.