ULA&#x27;s vehicles were designed around the RD-180 rocket engine [1][2]. This is an engine built and designed in Russia.<p>After Russia annexed Crimea, Congress banned the Pentagon from using Russian rocket engines. Russia responded by counter-banning the Pentagon from using its engines [3]. This made things complicated for ULA.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;RD-180" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;RD-180</a><p>[2] <a href="http:&#x2F;&#x2F;www.ulalaunch.com&#x2F;faqs-rd-180.aspx" rel="nofollow">http:&#x2F;&#x2F;www.ulalaunch.com&#x2F;faqs-rd-180.aspx</a><p>[3] <a href="http:&#x2F;&#x2F;www.bloomberg.com&#x2F;news&#x2F;articles&#x2F;2014-05-13&#x2F;russia-bans-rocket-engine-sales-to-u-s-military" rel="nofollow">http:&#x2F;&#x2F;www.bloomberg.com&#x2F;news&#x2F;articles&#x2F;2014-05-13&#x2F;russia-ban...</a>