Baer said the U.S. will "continue to make its case firmly" to Hanoi on various rights concerns, and will also raise Internet freedom and labor conditions in negotiations on the U.S.-backed Trans-Pacific Partnership, a regional trade pact that involves Vietnam.

NPR: US: Vietnam Backsliding On Human Rights

But they would also have to reconcile their differences, including over the Trans-Pacific Partnership (TPP), a regional free-trade grouping which Mr Hashimoto supports but Mr Abe opposes.

ECONOMIST: Japanese politics

"The United States will also be engaging with the Trans Pacific Partnership countries with the goal of shaping a regional agreement that will have broad-based membership and the high standards worthy of a 21st century trade agreement, " Mr. Obama said.

WSJ: U.S. to 'Engage' in Asia-Pacific Free Trade Pact

As a consequence, trans-border correlations, which would have benefited from regional treatment, were difficult to establish.

UNESCO: EARTH SCIENCES FOR SOCIETY

President Barack Obama said in Tokyo the U.S. will restart talks to potentially take part in a regional Asia-Pacific free trade agreement known as the Trans Pacific Partnership that currently includes Singapore, Brunei, Chile and New Zealand.

WSJ: U.S. to 'Engage' in Asia-Pacific Free Trade Pact