US President Barack Obama greets US Ambassador to Japan Caroline Kennedy (C) upon his arrival at Haneda International Airport in Tokyo April 23, 2014. [Photo/Agencies]

On the eve of Obama's arrival in Japan, 146 Japanese lawmakers visited en masse on Tuesday the notorious Yasukuni Shrine which honors 14 Class-A war criminals in World War II along with Japan's war dead, adding difficulties to Obama's already challenging seven-day Asian tour.

The visits followed an offering to the Tokyo shrine by Abe on Monday. Although having decided not to pay tribute in person this time, the prime minister dedicated a "masakaki" tree.

China-Japan relations

It is seen as an obvious attempt to play both ways -- avoiding further embarrassing Obama diplomatically and at the same time appeasing right-leaning forces domestically.

Japan has apologized for its wartime brutality on several occasions, but official acts such as visiting the Yasukuni Shrine and revising history textbooks to whitewash Japan's wartime atrocities have efffectively undercut its sincerity.

Regional countries, especially China and South Korea, are also particularly angered as Japan repeatedly refuses to accept the responsibility for sexual slavery during the war. Most of the sex slaves were women from China and Korea.

Japanese politicians' lack of sincerity in acknowledging its past brutal aggression have severely hurt the feelings of its victims, strained Japan's already fraught ties with Asian nations, and compounded their suspicion of Japan's intentions.

The latest shrine visits and offering have placed Obama, whose administration called Abe's shrine visit in December disappointing, on a tightrope.

Silence over the provocation will not only put a dent to Washington's moral authority around the region, but also land the US president in a delicate position as he will later travel to South Korea, a country that suffered greatly from Japanese aggression in WWII.

Washington is also worried that the provocation will further strain regional ties.

"We encourage Japan to continue to work with its neighbors to resolve concerns over history in an amicable way through dialogue, " a State Department spokesperson said Monday, commenting on the shrine visits.