By Linda Sieg and Elaine Lies
TOKYO (Reuters) - Remarks by aides to Prime Minister Shinzo Abe about U.S.-Japan ties and the wartime past are giving the Japanese leader a political headache as he seeks to soothe strains with key ally Washington amid rising regional tensions.
Investors have begun to worry that Abe, who took office in December 2012 pledging to revive the economy, is shifting more attention to his conservative agenda to bolster Japan's military and recast history with a less apologetic tone.
Japan-U.S. ties hit a bump when Abe visited Tokyo's Yasukuni Shrine on December 26, further straining relations with China and South Korea, which see the shrine as a symbol of Tokyo's past militarism because it honors wartime leaders as well as war dead.
The visit prompted a rare statement of "disappointment" from the United States. Diplomats hope an April trip by U.S. President Barack Obama will help ease bilateral strains and affirm the alliance, the linchpin of Tokyo's security policy.
Taking questions in parliament on Thursday, Abe said Japan had caused great pain in Asia and elsewhere in the past. His government would stick by past apologies and the door was open for dialogue with Beijing and Seoul, he added.
"As I've said before, in the past many nations, especially those in Asia, suffered great damage and pain due to our nation. Our government recognizes this, as have the governments that have gone before, and will continue this stance," Abe said.
"In the post-war era, we have deeply reflected on this and have built a free and democratic nation based on fundamental human rights. There will be no change in this path," he said.
Many of Abe's aides share a conservative agenda that includes forging a security stance less reliant on Washington and rejecting what they view as a "masochistic", overly apologetic interpretation of Japan's wartime deeds.
Those views are well known, but comments airing them publicly are gaining more attention than during Abe's first year in office, when his priority was efforts to revive the world's third biggest economy with his "Abenomics" mix of easy monetary policy and spending to boost growth.
On Thursday, Chief Cabinet Secretary Yoshihide Suga was forced for the second straight day to field questions about remarks from an Abe aide, this time by Abe's economic adviser Etsuro Honda.
In an interview with the Wall Street Journal, Honda defended the Yasukuni visit and said Japan needed a strong economy so it could build a more powerful military and stand up to China, the newspaper said.
The paper also said Honda wanted what it called "a nation that isn't beholden to the U.S. as a patron, and doesn't feel restrained by the sensitivities of its neighbors".
Suga said Honda's remarks had been distorted. "What I meant was not conveyed at all. I never said Abenomics had a military objective," Suga quoted Honda as telling him.
A spokeswoman for Dow Jones, the publisher of the Wall Street Journal said in a statement: "We stand by our story."
On Wednesday, Suga instructed Seiichi Eto, a special adviser to Abe, to remove a video message on YouTube in which he said he was "disappointed" by the U.S. statement on the premier's Yasukuni visit. The remarks echoed those made in an interview with Reuters and published earlier this month.
Suga told a news conference he had taken the step because Eto's video remarks - filmed in front of large posters showing Abe with his slogan "Take Back Japan" - were personal opinions not in line with the government's position.
Also on Thursday, NHK public TV Chairman Katsuto Momii was grilled by lawmakers again over his remarks, later retracted, that appeared to justify Japan's wartime military brothels by saying all warring nations had similar systems.
This week, however, Momii was quoted by media as telling an NHK board of governors meeting: "What's wrong with what I said?" He declined on Thursday to comment on those reports.
(Additional reporting by Tetsushi Kajimoto. Editing by Dean Yates and Ron Popeski)