Russia has again delayed the first flight of its already much delayed stealth strategic bomber, the Tupolev PAK DA.

The Kremlin signed a contract for the aircraft's production on April 13 with United Aircraft-Building Corporation. It expects the first experimental prototype of its next-generation strategic bomber -- which threatens to become its most expensive weapons system -- to be delivered in the early 2020s, said state-run media reports.

Like Us on Facebook

The first flight for this flying wing stealth bomber, which is expected to be outwardly similar to the U.S. B-2 Spirit, is scheduled for 2025.

Russia's defense industry partners completed research and development work for the project in 2016. Focus is now on the project's second stage: the development of design documentation and the manufacture of the aircraft's experimental prototypes.

Russia initially planned to begin testing the bomber between 2019 and 2020, but serial production for the Tupolev Tu-160 "White Swan" supersonic strategic bomber reportedly delayed the program. Russia plans to buy at least 50 more of the planes, which will be upgraded to the Tu-160M2 configuration.

The PAK DA project was almost cancelled in 2012, partly as a result of funding shortfalls.

PAK DA, which will replace both the turboprop-powered Tupolev Tu-95 "Bear" and the Tu-160, is being developed by the Tupolev Design Bureau. PAK DA stands for "Perspektivnyi Aviatsionnyi Kompleks Dal'ney Aviatsii" literally, "prospective aviation complex for long-range aviation."

This next-generation strategic bomber is expected to enter service with the Russian Air Force from 2025 to 2030. PAK DA will fly at subsonic speeds but a hypersonic version might be developed.

In its hypersonic version, PAK DA will be capable of launching nuclear weapons from space and can reach any part of the globe in one or two hours, said Colonel Alexei Solodovnikov, Representative of the Military Academy of the Russian Strategic Missile Forces.

PAK DA will be equipped with advanced precision guided weapons, including hypersonic weapons.

TagsRussia, Tupolev PAK-DA, United Aircraft-Building Corporation, B-2 Spirit, Tupolev Tu-160 "White Swan" supersonic strategic bomber, Tupolev Tu-95 "Bear"