Photo by Francis Chungg/UPI | License PhotoOct. 2 (UPI) -- The United States is blacklisting 44 individuals and firms accused of being involved in Iran's nuclear program and weapons procurement network, as the Trump administration continues to increase its so-called maximum pressure strategy on Tehran. Known by the initials SPND, the Tehran-based entity, founded in February 2011, is responsible for nuclear weapons development research. The sanctions comes after the State Department blacklisted three Iranian officials and one entity linked to SPND in May. In 2018, Trump unilaterally pulled the United States from an Obama-era accord, which aimed to prevent Iran from securing a nuclear weapon. "The United States is committed to denying Iran all paths to a nuclear weapon," Secretary of State Marco Rubio said in a statement.