Lew: Strong dollar 'good for the US... good for the world'

At a time when global central banks are moving to weaken their currencies, Treasury Secretary Jack Lew on Friday touted a stronger U.S. dollar.

Speaking a day after the European Central Bank announced an aggressive monetary easing program and a week after the Swiss National Bank shocked the world by removing the franc's peg to the euro, Lew told CNBC that as long is it happens for the right reason, a stronger dollar is a net positive.

"The strong dollar, as all my predecessors have joined me in saying, is a good thing. It's good for America. If it's the result of a strong economy, it's good for the U.S., it's good for the world," he said during an interview at the World Economic Forum in Davos, Switzerland. "If there are policies that are unfair, if there are interventions that are designed to gain an unfair advantage, that's a different story."

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The currency-weakening moves by the SNB, ECB and others across the globe have spurred talk about a renewed currency war as countries adopt a beggar-thy-neighbor policy to spur growth.

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In the U.S., the Federal Reserve has been on a seven-year campaign of easing that boosted its balance sheet past the $4.5 trillion mark. However, as the economy has outpaced others around the globe and the Fed plans its first rate hike after going to a near-zero policy in late 2008, the greenback has strengthened against its competitors.

Lew would not criticize other central banks, only saying that the Fed's moves were vital to getting the U.S. back on its feet after the financial crisis.

"There's a difference between domestic tools for domestic purposes and what are the unfair practices," he said. "Monetary authorities have to able to make their decisions in an independent way."

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On domestic matters, Lew expressed hope that the White House and Congress can make progress in 2015 on tax fairness.

President Barack Obama has been an advocate of eliminating specialized tax breaks that companies enjoy.

"Our economy will do better if we get rid of the loopholes that skew investment decisions and businesses concentrate on what they really should be concentrating on, which is what are the best investment decisions," he said.