The Defense Department is investigating a successor to an aircraft platform the U.S. Air Force uses to transport the U.S. vice president and other high-level government officials, Defense One reported Tuesday.

President Donald Trump’s fiscal 2018 budget proposal includes $6 million for the establishment of a project office that would identify possible replacement platforms for the C-32A Air Force Two, the report noted.

C-32A is a military variant of Boeing‘s 757 platform and designed to transport cabinet members, secretaries and other dignitaries to their intended destinations around the world.

The Air Force noted in the branch’s latest budget request that it wants its future transport aircraft to have greater communications, range and passenger space capacity than the current platform.

DoD also wants to replace the E-4B aircraft, nicknamed “doomsday plane,” which could function as a flying operations center to carry the defense secretary and president in the event of a nuclear war.

The Government Accountability Office has called on the Missile Defense Agency to address transparency issues with its cost estimates and test schedules related to the development of the Ballistic Missile Defense System.

GAO said in a report published Tuesday it made the recommendation due to lack of consistency and transparency with MDA’s cost estimates to back up its $1 billion budget request each year for BMDS tests.

MDA achieved some of its delivery and testing objectives for some BMDS components in fiscal year 2016, such as the completion of 10 test flights, implementation of five system level capabilities and updates to fielded interceptors, according to the report.

The congressional watchdog also found that MDA lacks sufficient insights from the Defense Department with regard to its acquisition strategies and design methods for several technological capabilities that MDA plans to integrate with BMDS.

GAO noted that MDA has spent approximately $123 billion on BMDS development since 2002 and plans to allocate another $37 billion to continue development work through FY 2021.

MDA conducted a live-fire test Tuesday to demonstrate its BMDS’ Ground-Based Midcourse Defense system component against an intercontinental ballistic missile target.

Navy Vice Adm. James Syring, director of the Missile Defense Agency, has said the live-fire test of the U.S. ballistic missile defense platform seeks to demonstrate the country’s readiness to counter intercontinental ballistic missile threats from potential adversaries, DoD News reported Wednesday.

MDA conducted the test Tuesday in which the BMDS’ ground-based midcourse defense platform helped guide a land-based interceptor with an exoatmospheric kill vehicle to engage and destroy an ICBM target that took off from Kwajalein Atoll in the Marshall Islands.

Syring told reporters the developmental test sought to replicate an actual operational scenario and that the BMDS platform “performed exactly as designed” based on collected data.

“I was confident before the test that we had the capability to defeat any threat that [North Korea or Iran] would throw at us and I’m even more confident today, after seeing the intercept test yesterday, that we continue to be on that course,” Syring said.

He noted the interceptor used in the test is the same design that will support the deployment of 44 interceptors by the end of the year.

Syring said MDA intends to conduct the next intercept trial either by the fall of 2017 or later next year with a plan to test adversary ICBM weapons by 2023.

The Missile Defense Agency conducted an initial live-fire test Tuesday of the Ground-based Midcourse Defense platform component of the ballistic missile defense system.

MDA said Tuesday a land-based interceptor that launched from Vandenberg Air Force Base in California used its exo-atmospheric kill vehicle to intercept and destroy an intercontinental ballistic missile that took off from a test site on Kwajalein Atoll in the Marshall Islands.

During the test, the GMD system devised a fire control strategy to intercept the ICBM target through the use of tracking data received from the Command, Control, Battle Management and Communication platform.

The Sea-Based X-band radar system located in the Pacific Ocean also assisted the GMD platform to acquire data and monitor the target.

MDA worked with the U.S. Air Force’s 30th space wing, U.S. Northern Command and the Joint Functional Component Command for Integrated Missile Defense to perform the Flight Test Ground-Based Interceptor-15 test.

MDA will use the data from the FTG-15 test to further evaluate the GMD system’s performance.

The BMDS’ GMD element works to help U.S. combatant commanders engage long-range and intermediate ballistic missile threats.