The consequences of this designation include a prohibition against American nationals engaging in transactions with Ishaq and the freezing of his property and interests in the United States or in the possession or control of US persons, the State Department said on Thursday.
Ishaq is a founding member and current leader of the banned LeJ. In 1997, Ishaq admitted his involvement in terrorist activity that resulted in the deaths of over 100 Pakistanis.
After spending 14 years in jail, Ishaq was freed in 2011 due to lack of evidence.
In February last year, Pakistani police arrested Ishaq in connection with bomb attacks on January 10 and February 16, 2013 in southwestern Quetta city that killed over 250 Pakistanis, a majority of them Shias. The LeJ claimed responsibility for the bombings.
In addition to Ishaq's designation as a global terrorist, the State Department reviewed and maintained the Foreign Terrorist Organisation designation of the LeJ.
The LeJ specialises in armed attacks and bombings and has claimed responsibility for numerous killings of Shia religious and civil society leaders in Pakistan.
It claimed responsibility for a 2013 attack in a crowded billiards hall in Quetta that resulted in the death of 80 people, the State Department said.
As a result of maintaining the FTO designation, the legal consequences of the measure remain in place, including the prohibition against knowingly providing, or attempting or conspiring to provide, material support or resources to LeJ, and the freezing of all LeJ assets under the control or possession of US financial institutions.
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