The point of the panel's investigation, Okada said, was to restore the public's trust in Japan's diplomacy.

NPR: Japan Confirms Secret Nuclear Pacts With U.S.

But this was no longer an issue, Okada said Tuesday, because the U.S. ordered its ships and planes to stop carrying tactical nuclear weapons in 1991.

NPR: Japan Confirms Secret Nuclear Pacts With U.S.

"People can come in and out in so many ways, " said Mr. Okada.

WSJ: Tiny New House, Old Kyoto Soul

Wynn Resorts denies wrongdoing in Macau and said Mr. Okada's challenges to the board process were an attempt to distract from his own alleged misdeeds.

WSJ: Wynn Defends Ouster of Key Investor

At a February 2011 board meeting, the board told Wynn Resorts that it shouldn't do business in the Philippines and told Mr. Wynn to cancel a planned meeting there with the president of the Philippines, which had been set up by Mr. Okada, Mr. Miller said.

WSJ: Wynn Defends Ouster of Key Investor

Wynn Resorts executives said not removing Mr. Okada could have put the company at risk in its efforts to get new casino licenses in the future.

WSJ: Wynn Defends Ouster of Key Investor

Mr. Miller said that company investigations related to Mr. Okada's business dealings in the Philippines began in July 2010 as the compliance committee looked into the possibility of Wynn Resorts becoming involved in a project Mr. Okada had initiated in the Philippines through Universal Entertainment.

WSJ: Wynn Defends Ouster of Key Investor

On the Tuesday conference call, Mr. Miller said the company had begun relaying its concerns about Mr. Okada's business practices to him before he had expressed concern about the donation.

WSJ: Wynn Defends Ouster of Key Investor

But Mr. Miller said the board's move to strike against Mr. Okada was necessary because the company has a provision in its articles of incorporation that allows it to remove a shareholder that might jeopardize existing or future licenses.

WSJ: Wynn Defends Ouster of Key Investor