Analysts say nuclear-powered cruise missile project believed tied to deadly blast at test site features many technical difficulties, and risks could outweigh gains

Authorities sow confusion with mixed messages in Arctic region where radiation spiked after blast at nuclear site

Radiation levels in area up to 16 times the norm after Thursday explosion at Arctic facility kills 5 scientists testing 'new weapons'

Nuclear Safety Institute of the Russian Academy of Sciences says residents are in no danger after deadly explosion near Severodvinsk

But expert denies president's claim that America has its own nuclear-powered cruise missile program

Scientists killed at secretive nuclear research facility were believed to be developing Burevestnik nuclear-powered cruise missile

7 were killed in blast that Moscow's TASS news agency reports was related to a 'radioisotope power source'

Authorities in the nearby city of Severodvinsk report a spike in radiation levels, but military denies it; post is later removed as residents rush to stock up on iodine

But alliance chief also places blame for demise of INF treaty on Moscow, expresses support for Washington

US to test new missile that had been banned under INF arms control treaty, Pompeo blames Russia for violating agreement for years; Moscow urges moratorium