WASHINGTON (AP) - Osama bin Laden is enlisting his top operative in Iraq, Abu Musab al-Zarqawi, to plan potential attacks on the United States, U.S. intelligence indicates.

Al-Zarqawi, who rivals bin Laden as the nation's public enemy No. 1, has been involved in attacks in the Middle East but has not been known before to have set his sights on the United States.

The Homeland Security Department issued a classified bulletin to officials about the intelligence, which spokesman Brian Roehrkasse described Monday as "credible but not specific."

The United States has no immediate plans to raise its national terror alert level, Roehrkasse said. However, the intelligence "reiterates the desire by al-Qaida and its associates to target the homeland," he said.

Bin Laden was in contact with al-Zarqawi within the past two months in an effort to enlist him in attacks, a U.S. official said on condition of anonymity. But events in Iraq, officials noted, have limited al-Zarqawi's ability to undertake attacks.

Al-Zarqawi is blamed for scores of attacks in Iraq and pledged allegiance to bin Laden and the al-Qaida network last year. Yet he has had differences with bin Laden, and his efforts are considered somewhat distinct from central al-Qaida operations.

Another administration official with access to the Homeland Security Department's bulletin said the intelligence indicates that al-Qaida has continued to encourage al-Zarqawi, who was born in Jordan, to get involved in terrorist actions against Americans outside of Iraq - including in the United States.