U.S. authorities believe the voice on a new audiotape coming from Iraq belongs to Abu Musab al-Zarqawi (search).
"It is believed to be him. We have tested it and it's a match,” one U.S. official told FOX News.
On the tape, which was posted on an Islamic Web site, al-Zarqawi denied that he is seriously injured. There have been conflicting postings about al-Zarqawi's health, including some saying he was shot in the lung.
On "FOX News Sunday," the chairman of the Joint Chiefs of Staff (search) conceded killing or capturing al-Zarqawi would be a milestone in fighting the insurgency.
“As the Al Qaeda leader and the foreign fighter leader, the jihad leader, in Iraq, ... he's an important target but even getting him, the movement will continue,” said Gen. Richard Myers. “Al Qaeda has a way of continuing to put people in those leadership positions.”
But Myers added that U.S. forces continued to put “24-hour-a-day, seven-days-a-week pressure on Zarqawi” and his organization. U.S. forces have rounded up about 600 of al-Zarqawi’s foot soldiers and at least a dozen of his closest aides.
Al-Zarqawi made the audio address to Usama bin Laden (search) on Monday to assure the Al Qaeda leader that he was in good health after being wounded in a gunbattle with U.S. troops.
"I am sure you have heard through the media that I was wounded and treated in a Ramadi hospital. I would like to assure you and the Muslim nation that these were pure allegations. It was a light wound, thank God. We are back fighting them in the land of the two rivers."
Al-Zarqawi addressed the message as "a letter from a soldier on the firing line to his commander."
He addressed bin Laden as his "emir," or commander, and asked bin Laden for guidance on conducting the insurgency. He said he sent bin Laden a war plan and asked for comments or approval.
Al-Zarqawi also claimed that his insurgent followers had won this month's bloody battle against U.S. troops at the town of Qaim near the Syrian border.
"It was one of the greatest battles of Islam," he said. "We would like to assure you that we are continuing on the path of jihad, we are committed to our pledge. We will either win or die trying."
FOX News' Bret Baier and The Associated Press contributed to this report.