Summit talks between Prime Minister Shinzo Abe and U.S. President Donald Trump earlier this month "allayed some of the concerns" about the bilateral alliance, but did not address Trump's criticism of Japanese trade practices, according to a report by the U.S. Congressional Research Service.

"Despite the positive atmospherics of the February 2017 summit, questions remain about how the relationship will fare under the Trump administration," said the report compiled by the service, which provides various inputs for U.S. legislators.

"Many analysts think that the issues of economic relations and of cost-sharing for defense will dominate the bilateral agenda, with the Trump administration demanding more from Japan," it said.