The United States has pressed Japan to achieve results concerning key bilateral issues before Prime Minister Shinzo Abe visits Washington, effectively setting hurdles for Tokyo, which wants enhanced ties with its main ally, diplomatic sources said.

The request, made earlier this month at a meeting of senior officials of the two countries, pertains to issues ranging from the contentious plan to relocate a U.S. military base in Okinawa to Japan's possible participation in the Trans-Pacific Partnership free-trade talks to Tokyo's restrictions on imported U.S. beef.

Abe, who took office in December following the Liberal Democratic Party's general election victory, originally hoped to meet President Barack Obama this month, apparently with the aim of showcasing stable bilateral relations at a time of soured ties with its neighbors, particularly China, over territorial disputes.