Defense Secretary Ash Carter has said the Pentagon must continue its purchases of Russian RD-180 rocket engines until the U.S. can find an alternative to the United Launch Alliance‘s Atlas V, Breaking Defense reported Wednesday.

Colin Clark writes that Carter told the Senate Appropriation defense subcommittee the military needs to buy at least 18 RD-180 engines or fly its payloads on Delta IV launch vehicles, which he claimed would require additional funds.

U.S. Air Force officials and some senior Pentagon officials have promoted the use of 18 RD-180 rocket engines until ULA, SpaceX and Blue Origin can offer new rockets that can carry military and other national security satellites into space, according to Clark’s report.

Moscow, Russia-based rocket engine company NPO Energomash designed and manufactures the RD-180 engines used on the Atlas V rocket.

The Government Accountability Office has recommended the Transportation Department define and document its roles and responsibilities for responses to cyber attacks against vehicles with an emphasis on systems that affect passenger safety.

GAO said in a report publicly released Monday it found modern vehicle interfaces for functions such as braking and steering that rely on software can be vulnerable to attacks via both short-range and long-range wireless connections.

Auditors at GAO consulted 32 selected industry stakeholders on practices that work to identify and mitigate potential vehicle cybersecurity risks such as lack of transparency, communication and collaboration on vehicles’ cyber defenses as the automobiles move through supply chains.

GAO found the DOT’s National Highway Traffic Safety Administration has worked to address potential vehicle cybersecurity issues and looks to determine its role in responding to a real-world attack.

GAO conducted the study to address available information about risks in modern vehicles that could affect passenger safety, practices and technologies to mitigate vehicle cybersecurity challenges and its impacts, opinions of selected stakeholders and DOT’s efforts to address vehicle cybersecurity.

Auditors also reviewed existing regulations and literature and interviewed DOT officials as well as other government heads from the Commerce Department, Defense Department, Department of Homeland Security, industry associations and various other subject matter experts.

The U.S. Army has tested its new air defense system that will work to protect soldiers from aircraft, cruise missiles, unmanned aircraft systems and artillery weapons once it becomes fully developed.

The Army said Monday the Integrated Fire Protection Capability Increment 2-Intercept — a joint project of the service branch’s Cruise Missile Defense Systems Project Office and Aviation and Missile Research, Development and Engineering Center — was tested at the White Sands Missile Range.

“If you go back and take a look at what has happened in terms of the threat over the last couple years, you’ll find that UAS systems and cruise missiles have really become a problem,” said Col. Terrence Howard, cruise missile defense systems program manager.

“We’re firing the entire kill chain and seeing what the end product looks like as we shoot at unmanned aerial systems and cruise missiles,” he added.

Tamera Adams, chief engineer for cruise missile defense systems projects, said the Army seeks to integrate IFPC Inc 2-I with the Army Integrated Air and Missile Defense system, Sentinel radar system and AIM-9X missile.

IFPC Inc 2-I, which is currently in full-featured prototype form, will work to fire multiple missile types in almost any direction through a Multi-Mission Launcher that is mounted on a medium tactical truck and designed to hold 15 missile tubes on a turret system, the Army noted.

The system has so far launched a Hellfire Longbow and a pair of AIM-9X Sidewinders against targets that simulate UAS or cruise missile threats, the service branch added.

The Army said it is scheduled to test IFPC Inc 2-I further to gauge its compatibility with other missiles and systems.