On Friday, the U.S. Justice Department charged four companies and five people with violating U.S. sanctions on Iran by illegally exporting sensitive technology to the country.

The 24-count indictment filed in the U.S. District Court for the Southern District of Texas alleges that beginning in July 2010, the Iranian procurement network obtained 28 million military-grade parts worth $24 million and evaded U.S. sanctions designed to ban the export of such technologies to Iran, reported Reuters.

The technologies included uninterruptible power supplies and microelectronics that can be used in surface-to-air missiles and were first sent to Taiwan and Turkey before being forwarded to Iran.

"Violations of the International Emergency Economic Powers Act not only can undercut the impact of U.S. sanctions, but can also serve to undermine U.S. foreign policy and adversely affect national security," Assistant Attorney General John Carlin said in a statement.

The charges come after the U.S. and five world powers reached a preliminary agreement with Tehran on April 2 in an effort to prevent Iran from obtaining nuclear weapons in exchange for the lifting of international sanctions. Negotiations are set to resume on April 21.

According to the press release: "The indictment alleges Houston-based company Smart Power Systems Inc. (SPS); Bahram Mechanic, 69, and Tooraj Faridi, 46, both of Houston; and Khosrow Afghahi, 71, of Los Angeles, were all members of an Iranian procurement network operating in the United States.  Also charged as part of the scheme are Arthur Shyu, and the Hosoda Taiwan Limited Corporation in Taiwan; Matin Sadeghi, 54, and Golsad Istanbul Trading Ltd. in Turkey; and the Faratel Corporation, co-owned by Mechanic and Afghahi in Iran."

Shyu and Sadeghi have not yet been apprehended and are believed to be outside the country.

The scheme operated as follows: Mechanic would receive commodity lists sought by the Iranian company Faratel, which served the Iranian Defense Ministry and the Atomic Energy Organization in Iran. Mechanic would then approve the orders and send them to Shyu in Taiwan, who would then purchase the commodities and send them to Turkey and then Iran.

If convicted, the defendants face up to 20 years in prison while the corporations face fines of up to $1 million for each U.S. sanction violation.