The treaty, which has limited the United States and Russia to 1,550 nuclear warheads each, expires on February 5 after negotiations stagnated under former president Donald Trump.

"The United States intends to seek a five-year extension of New START, as the treaty permits," White House press secretary Jen Psaki told reporters.

"This extension makes even more sense when the relationship with Russia is adversarial as it is at this time," she said.

She said that the new intelligence chief, Avril Haines, would also start an investigation into Russia's suspected poisoning of Kremlin critic Alexei Navalny, its alleged election interference and on whether Moscow was behind the massive SolarWinds hack.

She said the United States would also investigate bounties reportedly paid by Russian intelligence to extremists in Afghanistan who killed US troops.

"Even as we work with Russia to advance US Interests, so, too, we work to hold Russia to account for its reckless and adversarial actions," Psaki said.

Trump had unsuccessfully tried to widen New START to include China, whose nuclear program is growing but still far smaller than those of Russia and the United States.