WASHINGTON - The United States Thursday refused to break its silence on an escalating spying row which saw a furious Germany expel the top CIA agent in Berlin, even as lawmakers fretted about damage to ties with Europe's dominant power.
Germany's decision hinted at significant discord between two such close allies and signaled that Washington has failed to quell among Germans over its espionage activity.
But in contrast with the uproar in Berlin, Washington responded coolly, demurring when asked to comment on the expulsion, and choosing to instead stress the value of its relationship with Germany.
White House spokesman Josh Earnest said that any "comment on any reported intelligence acts would put at risk US assets, US personnel and United States national security."
He said contacts with Berlin on the issue were taking place through diplomatic, intelligence and law enforcement channels.
Though it is not being voiced publicly, there is frustration among some US officials about the high-profile way in which Germany has handled the latest spying row.
But Earnest said he did not want journalists to think "that we take this matter lightly."
National Security Council spokeswoman Caitlin Hayden said it was "essential that cooperation continue in all areas" with Germany.
State Department spokeswoman Jen Psaki said US Secretary of State John Kerry and German Foreign Minister Frank-Walter Steinmeier would likely speak in the coming days.
Rift between allies
US officials habitually decline to discuss intelligence issues in public.
But Germany's move elevated the spying row to a political and diplomatic confrontation between the United States, leader of the West, and Europe's most influential power -- as both nations work together to confront global crises, including the showdown with Russia over Ukraine.
Transatlantic intelligence cooperation between the United States, Germany and other key European nations is also crucial to detecting terror plots, as fears rise that Muslim radicals from Syria holding Western passports could be plotting new attacks.
The US stance was likely to do little to quell outrage in Germany, where there are demands for a public sign of American contrition.
Anger over US espionage was first stirred last year by revelations of mass National Security Agency (NSA) data collection on German communications networks, leaked by fugitive Edward Snowden.
Claims that Washington had tapped German Chancellor Angela Merkel's mobile phone took the row to a new level and ill-feeling had barely subsided when German authorities arrested a man reportedly accused of being a double agent for the CIA.
With Merkel under immense political pressure, German patience snapped amid claims a second government official was being investigated for allegedly passing secrets to the United States.
US lawmakers worried
The sudden escalation of the crisis sparked alarm among top US lawmakers at the wider diplomatic damage the spy row was beginning to wreak.
Democrat Dianne Feinstein, who chairs the Senate Select Committee on Intelligence, said she was "deeply concerned," but could not talk about it.
The top Republican on the Committee, Senator Saxby Chambliss, said he could not remember a case where the CIA station chief was expelled from a host country.
Another committee member, Republican Senator Jim Risch, told AFP that "this is a situation that's starting to get out of hand."
"The executives of both countries need to sit down at a table and try to get this resolved."
One of President Barack Obama's earliest political allies, Democratic Senator Tim Kaine of Virginia, told AFP that the row was "very discouraging."
"I think the US administration has to sit down in face-to-face meetings with Germany and try to find a path going forward.
"I definitely think the president should deal directly with Angela Merkel on this. I think it's very important we do because the relationship is too important to let it fray over this."
The White House said there were currently no plans for Obama and Merkel to speak.
Officials have said that Obama did not know about the new spying affair when he spoke by telephone to Merkel a week ago.
The two leaders have had a close relationship, and Obama has made it known that Merkel is one of the world leaders he most respects.
But the political pressure on the German leader is intense over the issue -- especially after Washington declined to agree to conclude a "no-spy" deal with Germany similar to the ones it has with Britain, Australia, Canada and New Zealand.
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