WASHINGTON, Jan. 21 (CNA) - US President Joe Biden on Thursday (Jan 21) proposed a five-year extension with Russia of New START, days before the expiration of the last nuclear reduction treaty between the two powers, but vowed to press Moscow hard on a host of concerns.

The announcement on the first full day of Biden's presidency is intended to prevent a nuclear arms race but makes clear he will not attempt a "reset" of relations as attempted in varying forms by every post-Cold War president.

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

Russian President Vladimir Putin himself had offered Trump a five-year extension, the maximum allowed under the treaty that was signed in 2010 in Prague by former president Barack Obama.

"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, who was arrested Sunday on his return to Moscow, as well as on Russia's alleged election interference and on whether it was behind the massive SolarWinds hack that shook the US government and corporations.

Psaki said the United States would also investigate bounties reportedly paid by Russian intelligence to extremists in Afghanistan as rewards for killing 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.

Biden's approach is almost the mirror opposite from that of Trump, who voiced fondness for Putin even as his administration ripped up remaining arms control deals with Russia.

US intelligence concluded that Russia meddled in the 2016 election to back Trump, including through social media manipulation. Psaki said the new probe would assess any role in last year's election.