The U.S. Air Force June 2 launched a competition to develop a new rocket propulsion system, citing an "urgent need" to end reliance on Russian engines to launch military and intelligence satellites.

Lieutenant General Samuel Greaves, who heads the Air Force's Space and Missiles Systems Center, said proposals from private companies are due by June 23. The government hopes to divide $160 million in contracts among as many as four bidders.

The Air Force is scrambling to meet a congressional deadline for ending use by 2019 of Russian-built RD-180 engines to launch U.S. military and intelligence satellites. Congress enacted the ban after Russia last year annexed the Crimea region of Ukraine.

Russia's actions sparked concerns about relying on the Russian engines to power the Atlas 5 rocket built by United Launch Alliance, a joint venture of Lockheed Martin Corp and Boeing Co.

Based on reporting by Reuters and Air Force Link