"Russia may retaliate by cutting off our supply of RD-180 engines. Imported Russian RD-180s power the first stage of the American Atlas V rocket; the Atlas V launches our military satellites. If Putin does threaten our rocket shipments, we can dip into the two-year store that has been stockpiled for just such an occasion -- and two weeks ago, SpaceX CEO Elon Musk testified to Congress that his American-made Falcon rockets are ready to take over (for about $300 million less per flight than an Atlas launch costs taxpayers now)."
Orbital Drops Antitrust Lawsuit Against ULA, Space News
"Orbital is considering the RD-180 as a replacement for the AJ-26 engines that power the main stage of the company's Antares medium-lift rocket. Each Antares rocket uses two AJ-26 engines, which are actually Soviet-vintage NK-33 engines refurbished by Aerojet Rocketdyne of Sacramento, Calif. Orbital has secured only enough AJ-26 engines for the eight cargo-delivery missions to the international space station the company owes NASA through 2016 under a $1.89 billion Commercial Resupply Services contract signed in 2008."
Keith's note: Wouldn't it be prudent to start building Americanized versions of these engines - or develop home grown designs?