A U.S. officials says China's newest nuclear-powered submarine in its fleet sank in spring while docked at a pier but Chinese government officials have taken steps to cover it up.

The U.S. official said it was "not surprising" that China's navy would conceal it. The submarine's current status is unknown.

A senior U.S. defense official says satellite imagery shows that China's newest nuclear submarine sank while under construction.

The Kremlin says that changes in Russia’s nuclear doctrine are intended to discourage Ukraine’s Western allies from supporting attacks on Russia

The Kremlin said on Thursday that changes to Russia's nuclear weapons doctrine outlined by President Vladimir Putin should be considered a signal to Western countries that there will be consequences if they participate in attacks on Russia.