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TOKYO (Reuters) - Japanese Finance Minister Taro Aso spoke by phone with newly sworn-in U.S. Treasury Secretary Steven Mnuchin on Thursday but they did not discuss currencies, a Japanese finance ministry official said.

The U.S. Senate on Monday voted to confirm the former Goldman Sachs banker as Treasury secretary, installing the Trump administration’s point-man on tax reform, financial deregulation and economic diplomacy efforts.

No other details of the call were immediately available, but economists and traders will be closely watching U.S.-Japan relations for any signs of friction over currency and trade policy.

U.S. President Donald Trump refrained from criticizing Japan’s currency policy or its trade surplus with the U.S. when he met Japanese Prime Minister Shinzo Abe last week in Washington and Florida.

This gave many Japanese officials hope that Japan can maintain good economic relations with the U.S., but some economists worry the U.S. government could still adopt a protectionist stance on trade.

Before meeting Abe, Trump shocked Japanese policymakers by saying the Bank of Japan’s quantitative easing amounts to competitive currency devaluation.

Trump has also expressed concern about the low number of U.S. auto exports to Japan, which some saw as a sign he wants to reduce the U.S. trade deficit with Japan.

In reply, Japanese officials said monetary policy is aimed at ending deflation and pointed out that Japan poses no tariffs on U.S. auto imports.