WASHINGTON (AP) — Working to prevent tension with a treaty ally, Vice President Joe Biden reassured Japanese Prime Minister Shinzo Abe on Tuesday that the U.S. limits its surveillance of friendly nations, after leaked documents showed U.S. spying on Japanese officials and companies.

Abe had expressed deep concern about the documents WikiLeaks published last week, and vowed to bring up the issue with the U.S. The response appeared to come in the phone call with Biden, who has an established relationship with Abe after years of in-person diplomacy.

"The vice president reaffirmed the United States' commitment made by President Obama in a 2014 presidential directive to focus our intelligence collection on national security interests," the White House said in a brief statement describing the call.

The Japanese prime minister's office said Wednesday that Biden also apologized for causing trouble in Japan, without mentioning a specific incident. It added that Abe told Biden that if the allegations are true, it would threaten the trust between the two countries, so he expects the U.S. to investigate the reports and respond appropriately.

In his 2014 directive and an accompanying speech, Obama promised the U.S. would no longer monitor leaders of "friends and allies" without a compelling reason, following devastating leaks from former National Security Agency contractor Edward Snowden that caused diplomatic rifts with Germany and Brazil. The White House has also said the U.S. doesn't conduct spying to gain an economic edge.

The White House offered few details about the call, but said Biden had "underscored our strong commitment to the U.S.-Japan alliance" and thanked Abe for partnering with the U.S.

The effort to mollify Japan comes as the U.S. struggles to finalize a major trade deal that forms the economic centerpiece of Obama's effort to increase U.S. influence in Asia. In Hawaii last week, negotiators from a dozen Pacific Rim countries failed to reach a deal on the Trans-Pacific Partnership, which is held up in part over disagreements about access to Japan's auto markets.

The leaked documents include what appear to be five U.S. National Security Agency reports, four of which are marked top-secret, that provide intelligence on Japanese positions on international trade and climate change. They date from 2007 to 2009.

WikiLeaks also posted what it says is an NSA list of 35 Japanese targets for telephone intercepts, including the Japanese Cabinet office, Bank of Japan officials, Finance and Trade Ministry offices, the natural gas division at Mitsubishi and the petroleum division at Mitsui.

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Associated Press writer Ken Moritsugu in Tokyo contributed to this report.

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Reach Josh Lederman on Twitter at http://twitter.com/joshledermanAP