John Kerry

WASHINGTON — Secretary of State John Kerry landed in Rome and Paris to talk about Mideast peace, Syria and Iran but was confronted by outrage over the sweep and scope of U.S. snooping abroad. President Barack Obama already has defended America’s surveillance dragnet to leaders of Russia, Mexico, Brazil, France and Germany and was even quizzed about it during his birthday appearance on late-night television.

In the short run, Obama and Kerry are trying to quell international anger over classified disclosures by former National Security Agency contractor Edward Snowden. Longer term, Snowden’s revelations about NSA tactics — that allegedly include tapping up to 35 world leaders’ cellphones — threaten to undermine U.S. foreign policy in a host of areas.

It’s the vacuum-cleaner approach to data collection that has rattled foreign allies. “The magnitude of the eavesdropping is what shocked us,” former French Foreign Minister Bernard Kouchner said in a radio interview. “Let’s be honest, we eavesdrop too. Everyone is listening to everyone else. But we don’t have the same means as the United States, which makes us jealous.”

The disclosures not only raise the question: Where in the world isn’t the NSA? They also sparked debate about whether tapping the phones of allies is a step too far. The question might already be moot. The British ambassador to Lebanon, Tom Fletcher, tweeted this week: “I work on assumption that 6+ countries tap my phone. Increasingly rare that diplomats say anything sensitive on calls.”

Diplomatic relations are built on trust. If America’s credibility is in question, the U.S. will find it harder to maintain alliances, influence world opinion and maybe even seal trade deals.

Spying among allies is not new. Madeleine Albright, secretary of state during the Clinton administration, recalled being at the United Nations and having the French ambassador ask her why she said something in a private conversation that the French had apparently intercepted. The French government protested revelations this week that the NSA had collected 70.3 million French-based telephone and electronic message records in a 30-day period.

Albright says Snowden’s disclosures have been very damaging to U.S. policymakers.

“A lot of the things that have come out, I think are specifically damaging, because they are negotiating positions and a variety of ways that we have to go about business,” Albright said at a conference hosted by the Center for American Progress in Washington. “I think it has made life very difficult for Secretary Kerry.”

The spy flap could give the Europeans leverage in talks with the U.S. on a free-trade agreement, which would join together nearly half of the global economy.

To Henry Farrell and Martha Finnemore at George Washington University, damage from the NSA disclosures could “undermine Washington’s ability to act hypocritically and get away with it.”

The danger in the disclosures “lies not in the new information that they reveal but in the documented confirmation they provide of what the United States is actually doing and why,” they wrote in Foreign Affairs. “When these deeds turn out to clash with the government’s public rhetoric, as they so often do, it becomes harder for U.S. allies to overlook Washington’s covert behavior and easier for U.S. adversaries to justify their own.”