Washington ? In a letter to his top deputy in Iraq, al-Qaida’s No. 2 leader said the United States “ran and left their agents” in Vietnam and the jihadists must have a plan ready to fill the void if the Americans suddenly leave Iraq.

“Things may develop faster than we imagine,” Ayman al-Zawahri wrote in a letter to his top deputy in Iraq, Abu Musab al-Zarqawi. “The aftermath of the collapse of American power in Vietnam – and how they ran and left their agents – is noteworthy. … We must be ready starting now.”

Senior U.S. military commanders have said that Iraqi security forces are improving significantly and some U.S. forces could return home early next year. Yet skeptics have raised concerns about whether such statements simply let the insurgency know how long they must wait for the U.S. to leave.

In a letter taking up 13 typed pages in its English translation, al-Zawahri also recommended a four-stage expansion of the war that would take the fighting to neighboring Muslim countries.

“It has always been my belief that the victory of Islam will never take place until a Muslim state is established … in the heart of the Islamic world,” al-Zawahri wrote.

The letter laid out his long-term plan: expel the Americans from Iraq, establish an Islamic authority and take the war to Iraq’s secular neighbors, including Lebanon, Jordan and Syria.

The letter is dated July 9, and was acquired during U.S. operations in Iraq. It was written in Arabic and translated by the U.S. government. The Pentagon briefed reporters last week on portions of the document. The full text was not available until Tuesday.

In a statement, the National Intelligence Director’s office said the letter “has not been edited in any way” and its contents were released only after it was clear no military or intelligence operations would be compromised.

House Intelligence Chairman Peter Hoekstra, R-Mich., said his committee is reviewing the letter, but he cautioned “against reading too much into a single source of intelligence.”

Al-Zawahri commented on the media’s role in the frey.

“More than half of this battle is taking place in the battlefield of the media,” al-Zawahri wrote. “We are in a media battle in a race for the hearts and minds of our umma,” or community of Muslims, he wrote.

The line is an apparent reference to a phrase – “hearts and minds” – often used by President Bush.