The U.S. designation “is a way of avoiding biting the bullet, which is compelling Pakistan to act on this issue in a responsible way,” said Praveen Swami, an editor at the Hindu newspaper in India and renowned national security analyst, in an interview. “Granted, there are no easy solutions. But what is being done to persuade the Pakistani government that if they don’t do anything about it there will be a result?”

A spokesman at the Pakistani embassy did not respond to a request for comment.

The sanctions will have the political effect of exposing the Lashkar leaders and disrupting their activities, said Treasury spokesman John Sullivan.

Certainly, the designation contradicts the repeated claims by the Pakistani government that it has cracked down on Lashkar.

Based on intelligence and evidence culled from U.S. counterterror agencies, the Treasury statement describes a sophisticated and brazen militant group that operates air and naval wings, raises funds and recruits fighters across Pakistan and overseas, and even pays for favorable media coverage.

The most embarrassing allegations for Pakistan focus on Mir. He has been a target of Western and Indian law enforcement for more than a decade and technically been a fugitive even before late 2008, when Indian phone wiretaps broadcast worldwide caught him directing the slaughter by 10 gunmen in Mumbai from a command post in Karachi.

The U.S. government indicted Mir, two other chiefs and an ISI major last year. In 2007, a French court convicted Mir in absentia on charges of leading American, British, French and Australian recruits in a bomb plot and weapons procurement.

Yet, law enforcement officials complain that Mir, allegedly a close associate of the ISI, engages in open extremist activity from his home in Lahore. And the Treasury statement reinforces those allegations. As of 2010, the statement says, Mir was responsible for the security of Zaki ur-Rehman Lakhvi, a Lashkar military chief jailed in early 2009 for the Mumbai attacks. It was one of the few significant arrests in the case, but the Pakistani trial of Lakhvi and six others appears stalled.

The Treasury statement indicates that Mir has worked with Lakhvi while he is in custody. The allegation reinforces the account of Mir’s former prize operative David Coleman Headley, a confessed American agent of Lashkar and the ISI who pleaded guilty in Chicago federal court to a central reconnaissance role in the Mumbai plot and a follow-up plot against Denmark.

Headley told interrogators after his arrest in late 2009 that Mir had visited the jailed Lakhvi, a sign that Mir enjoys high-level protection, according to an interrogation report by India’s National Investigation Agency as well as ProPublica interviews with U.S. and Indian counterterror officials. The comfortable conditions of Lakhvi’s custody have enabled him to run Lashkar operations through cell phone calls and meetings, according to those investigators and a high-level U.S. report viewed by ProPublica.

Over the years, the Pakistani security forces have periodically placed Lashkar leaders in custody, usually short-term house arrest. Because of the close alliance between Lashkar and the ISI, Lashkar militants often provide additional security for those chiefs, escorting them to court, vetting visitors and coordinating with jailers, according to U.S and Indian counterterror officials.

“Lakhvi is in a loose environment in which he is allowed to make phone calls,” an Indian counterterror official said. “If this allegation about Sajid Mir is true, that means there is some kind of access in which he is allowed to have responsibility for the protection of Lakhvi. It is security coordinating between the government apparatus and the Lashkar apparatus.”

As of last year, Mir also continued to recruit militants, lead Lashkar external operations and direct terror plots, the Treasury statement says.

Another Lashkar leader designated this week allegedly has direct ties to extremist activity in the United States. Talha Saeed, the son of Lashkar spiritual leader Hafiz Saeed, has overseen the group’s media operations on the Internet, radio programs and a magazine as well as relations with the press, according to Treasury. In April, the State Department offered a $10 million reward for the capture of the elder Saeed, who holds defiant mass rallies in Pakistan.

“[Talha] Saeed founded an LET front group, which he planned to use to pay journalists to write favorable stories on behalf of LET as of early 2009,” the statement says.

The younger Saeed also figured prominently in a recent terrorism case in the Virginia suburbs of Washington, D.C. A Pakistani immigrant named Jubair Ahmad pleaded guilty in April to material support of terrorism for training in Lashkar camps and working with Saeed from the United States to prepare propaganda videos.

In response to foreign pressure, Lashkar has engaged in subterfuge to shield its activities, according to U.S. authorities. The Treasury Department accused a veteran Lashkar spokesman named Abdullah Muntazir of faking a defection from Lashkar in order to enhance his credibility and secretly engage in propaganda.

“Muntazir has been an LET media official since at least 1999,” the Treasury statement says. “As of 2011, Muntazir was still an LET media official, despite presenting himself to the media as an independent scholar on militancy issues, including those relating to LET.”

Unlike al Qaeda and the Taliban, Lashkar has preserved an alliance with the Pakistani government because it largely refrains from terror activity in Pakistan.

The U.S. terrorist designation may not have a resounding impact, but it is a necessary step in a long-term U.S. campaign against a terror organization with worrisome clout, said Stephen Tankel, a professor at American University who is considered one of the top experts on the militant organization.

“This is part of an ongoing strategy,” Tankel said. “It is intended to make Lashkar’s domestic and international operating environment just a bit more difficult and to put additional pressure on Pakistan to take serious action. And in the event there was a shift in Pakistan’s calculus and it chose to launch a real crackdown on Lashkar, these steps could aid that action.”