WASHINGTON - US President Joe Biden reiterated Tuesday that there is no intention in his administration or within the North Atlantic Treaty Organization (NATO) to send troops into Ukraine, but that Russia will face serious economic consequences if it invades the former Soviet republic.

"We have no intention of putting American forces or NATO forces in Ukraine," Biden told reporters when he was at a store in Washington buying gifts for his wife and grandson. "But I said there are going to be serious economic consequences if (Russian President Vladimir Putin) moves" Russian troops into Ukraine.

Biden's remarks came one day after Defense Secretary Lloyd Austin placed some 8,500 US troops to be on "heightened preparedness to deploy" to Europe, citing "Russia's continuing provocations along its border with Ukraine."

Biden told reporters that the ready-to-deploy action is a "NATO operation" rather than "a sole US operation," and that it is a manifestation of Washington's commitment to NATO's Article VI collective defense obligation.

Biden said if Putin "continued to build up" Russian forces along Ukraine's border or if he "was to move" the troops into Ukraine, the United States will be "reinforcing" its troops.

Asked whether he is considering sanctioning the Russian president personally if he orders the invasion of Ukraine, Biden said: "Yes, he would receive that."

The president didn't give a definitive answer to whether the possibility of Russia invading Ukraine is increasing, decreasing or steady, saying what's in Putin's mind remains vague, and that "it all comes down to his decision."

Earlier in the day, White House press secretary Jen Psaki called a Russian invasion of Ukraine "imminent."

"But again, we can't make a prediction of what decision President Putin will make. We're still engaged in diplomatic discussions and negotiations," she said during a press briefing at the White House.