US space agencies need additional Russian-made RD-180 rocket engines until a domestically produced equivalent is ready for use, the head of US Space Command said June 26.

"Without access to the RD-180... we severely limit our assured access [to space], undermine the competition we have worked so diligently to enable and will have traded one monopoly for another in the medium and intermediate vehicle classes," Gen. John Hyten said at a House Armed Services Committee hearing, National Defense magazine wrote on Friday.

The nine RD-180 rocket engines available will not ensure access to space for the United States national security needs, said Hyten. He supported the

Defense Department request to fulfill the 2012 purchase of additional RD-180 rocket engines in order to allow the ULA to participate competitively until a new launch system is available to deliver necessary space capabilities.

Congress earlier prohibited the use of the Russian-made engines for heavy lift rockets after 2019. Now, the aeronautic industry is working to produce a domestic version, but there are concerns that a replacement will not be ready in time. That may leave SpaceX, founded by billionaire Elon Musk, alone in offering heavy lift services if its Falcon Heavy is developed by then, the magazine noted.

"If the current law is not modified, America will not have assured access to space and competition will have been unintentionally eliminated, giving the new entrant a monopoly," Tory Bruno, President and CEO United Launch Alliance, said referring to launch provider SpaceX.

US federal law requires two independent providers of launch systems for access to space. ULA manufactured Atlas V and Delta IV launch systems, which use the Russian made RD-180 engine, currently carry two-thirds of US national security payloads.

Source: Xinhua News Agency