The Russian government is preparing to begin deliveries of S-300 surface-to-air missile systems to Iran by the end of of 2016.

The contract between the two countries marks the end of legal disputes that delayed the procurement. The United States, Israel and their partners are expected to oppose the deal, the Financial Times reported.

"The contract has been signed," Rostec CEO Sergey Chemesov said in a statement. "I think by the end of next year we will start deliveries of the S-300."

The initial contract for the missile defense systems was signed in 2007, but U.N. sanctions against Iran halted the deal. Russian President Vladimir Putin repealed the ban on the delivery in April. Iranian government officials agreed to abandon their nuclear ambitions in exchange for sanctions relief.

The S-300 missile defense system is a series of long-range surface-to-air missile complexes, first used by the Soviet Union in 1979. The Russian armed forces have since modified the system to fit modern uses, the BBC reported.

The missile defense system engages targets with the help of a long-range surveillance radar, which can follow targets at a range of 185 miles and relays information to a command vehicle, which gives the order to launch missiles. In addition to tracking the target, the radar is used to guide missiles toward the target, able to engage up to six targets at a time.

Military experts have compared the system to the U.S.-made Patriot Air and Missile Defense System.