The U.S. government yesterday offered a $10 million reward for information leading to the arrest of Hafeez Saeed, the spiritual chief of Pakistan's Lashkar-i-Taiba militant group and an alleged mastermind of the 2008 Mumbai terror attacks. A yearlong investigation by ProPublica and PBS' Frontline explored the role of American David Coleman Headley in planning the three-day raid by gunmen of Lashkar-i-Taiba supported by Pakistan's intelligence service, the ISI.

As we reported, Headley revealed that Saeed helped plan the Mumbai attacks. He credited Saeed for inspiring him to jihad and, after his arrest, told interrogators about Saeed's ties to Pakistani intelligence. "He is very close to ISI," Headley said of Saeed. "He is well protected." (For more, see our complete coverage.) The U.S. State Department also offered a reward for Hafiz Abdul Rahman Makki, another senior Lashkar boss.

The announcements show how much U.S-Pakistani relations have deteriorated as the Obama administration has taken a harder line with Islamabad. When Headley was indicted in late 2009 for conducting reconnaissance for the attacks that killed 166 people, U.S. authorities tried to avoid diplomatic tensions by refraining from publicly identifying Lashkar masterminds involved in the deaths of six Americans and other Westerners as well as Indians in Mumbai.

Last year, U.S. prosecutors indicted midlevel Lashkar chief Sajid Mir, an ISI officer named Major Iqbal and two other accused plotters. Prosecutors detailed the ISI's central role in the attacks during a federal trial in Chicago of an accomplice of Headley. The case, along with the discovery of Osama bin Laden in a military garrison town, raised alarming questions about the ISI's support for terrorism and escalated tensions with Pakistan.

Although U.S. prosecutors have not indicted Saeed, the offer of the reward is clearly intended to increase pressure on Lashkar, the ISI and the Pakistani government. Saeed is a powerful public figure in Pakistan and has held mass rallies in recent months in which he denounced the West and India.

Pakistani authorities have occasionally placed him under brief house arrest, but Western and Indian counterterror officials say he continues to run Lashkar with the support and protection of the Pakistani government. Pakistani authorities have also refused to arrest Mir, Major Iqbal and other suspects despite abundant evidence against them. Their whereabouts, like Saeed's, are well-known.

The trial in Pakistan of Zaki-ur-Rehman Lakhvi, Lashkar's military chief, and a few others charged in the Mumbai case has stalled. As ProPublica reported last year, Lakhvi continues to lead the group from jail and authorities have refused to confiscate his cell phone despite a direct appeal from a senior U.S. official to the director of the ISI.

"This is a name-and-shame tactic directed at two of the most public figures in Lashkar," said Stephen Tankel, an American University professor and author of the book "Storming the World Stage" about the group. "It appears to be part of a long-term effort to exert pressure on the Pakistani government."