LeVine says she has been trying to "turn the page" on tensions between the two nations after a crackdown on offshore tax evasion focused mainly on Switzerland, the biggest haven with assets of more than $2 trillion. Wegelin & Co., the country's oldest bank, closed its doors after pleading guilty in New York in 2013 to helping hundreds of taxpayers evade taxes.
The Justice Department's approach is about bringing Americans to justice, rather than singling out Switzerland's financial institutions, said LeVine.
"It isn't about Swiss banks," she said. "It is about tax evasion and the facilitation of tax evasion. If the money has left an account here in Switzerland, part of the effort is to understand where the money has gone."
Less than 5 percent of the $167 billion of fines and penalties levied by the U.S. government since the global financial crisis were imposed on Swiss banks, according to LeVine, with about 85 percent on U.S. institutions.
UBS Group, Switzerland's largest bank, paid $780 million in 2009 and turned over the details of thousands of client accounts in exchange for a deferred prosecution agreement. Five years later, second-ranked Credit Suisse agreed to pay $2.6 billion in penalties and pleaded guilty to helping Americans cheat on their taxes.
Other banks, including Baer and HSBC Holdings's Swiss unit, face ongoing criminal investigations and are on "their own timeline" in terms of finding a settlement, according to the ambassador.
LeVine defended the importance of the Justice Department's pursuit of corruption within FIFA, days after the Swiss lawyer appointed to lead the soccer body's reform committee publicly questioned whether the U.S. should be doing so.
There is a U.S. "nexus" to all seven of the soccer executives that American prosecutors are seeking to have indicted to face charges of racketeering and money laundering, LeVine said. The Swiss Federal Office of Justice said it expects to make a decision next month on the remaining five who are fighting their extradition from Switzerland.
The U.S. case against the FIFA officials is about "rooting out corruption in a sport beloved by hundreds of millions of people around the globe, including kids of all shapes and sizes and colors," she said.
Francois Carrard, the new head of FIFA's reform committee, asked why the U.S. is pursuing FIFA so doggedly when interviewed by Swiss newspaper Le Matin last week.
"For the U.S., soccer does not have the same weight as baseball, basketball or American football," he told the newspaper. "There, it's just an ethnic sport, for girls at school."
Switzerland acted unilaterally this month in lifting suspended sanctions against Iran after the Gulf state sealed an accord with the U.S. and other world powers in July to curb its nuclear program. LeVine said her embassy was not consulted or given pre-warning on the decision by Switzerland's Federal Council to become the first nation to remove Iran sanctions.
Switzerland has served as the U.S.'s "protecting power" in Iran since the hostage crisis in 1980, taking responsibility for most consular matters for American citizens visiting or residing in Iran.
While the U.S. and European Union are negotiating a trade agreement known as the Transatlantic Trade and Investment Partnership that could squeeze Swiss exporters, LeVine said the bilateral economic relationship is strong.
"Once that agreement is signed, then there will be an exploration of options and opportunities with the Swiss," she said.
- With assistance from James Kraus and Giles Broom in Geneva and David Voreacos in federal court in Newark, N.J.