WASHINGTON (Kyodo News International) — Agriculture Secretary Tom Vilsack on Tuesday acknowledged the difficulty in convincing Japan to fully reopen its beef market to imports from the United States.

"I have no illusions how easy this is going to be. It's obviously going to be difficult," he told a press briefing ahead of his trip to Japan next week.

But Vilsack said he expects "forward progress" regarding Tokyo's controls on U.S. beef imports, which stem from fears about mad cow disease, when he meets Japanese officials such as Agriculture, Forestry and Fisheries Minister Hirotaka Akamatsu.

"We would never make a demand. This is a relationship that has been bound in friendship for an extended period of time, and it is really about friends basically talking to each other about each other's needs," he added.

Japan and the United States are at odds over Washington's insistence that Tokyo abolish its ban on imports of U.S. beef from cattle aged over 20 months.

Tokyo suspended all beef imports from the United States after the first U.S. case of bovine spongiform encephalopathy, commonly known as mad cow disease, was found in 2003.

Japan, which had until then been the U.S. cattle industry's biggest export market, later partially reopened the beef market with certain restrictions, including an age limit.

Vilsack is due to travel to Japan for five days starting next Monday as part of a new initiative by President Barack Obama's administration to double U.S. exports over five years.

The trip comes as the U.S. Congress ratchets up pressure on Tokyo to lift the ban as soon as possible ahead of the midterm election in November.

Earlier this month, two resolutions were presented to call on Japan to fully reopen its beef market to U.S. beef imports, with an author of one of them saying, "For several years now, Japan has used nonscientific standards to restrict access to high-quality U.S. beef products."

A group of Democratic lawmakers said last week they had sent a letter to Obama citing the need to tackle foreign countries' restrictions on U.S. beef imports, apparently including Tokyo's import ban.