U.S. President Joe Biden said on Tuesday he would consider personal sanctions on President Vladimir Putin if Russia invades Ukraine.

If Russia were to move into Ukraine with the estimated 100,000 soldiers it has massed near the border, Biden said it would be the "largest invasion since World War II " and would "change the world."

Speaking to reporters, Biden was asked if he would see himself imposing sanctions on Putin directly if Russia invaded Ukraine. "Yes," he responded. "I would see that," according to a Reuters report from Washington.

The Russian president’s opponents claim that he holds a lot of assets overseas and the western leaders think that such personal sanctions could hit Putin where it hurts most.

Direct U.S. sanctions have earlier been imposed on Venezuela's Nicolas Maduro, Syria's Bashar al-Assad and Libya's Muammer Gaddafi.

The rare sanctions threat came as the Pentagon has put on alert about 8,500 U.S. troops in Europe and the United States to be ready to deploy to NATO's eastern flank if needed.

Biden said on Tuesday he may deploy U.S. troops in the nearer term but ruled out sending unilateral U.S. forces to Ukraine, which is not a NATO member.

"There is not going to be any American forces moving into Ukraine," he said.

Russia denies planning an attack and says the crisis is being driven by NATO and U.S. actions. It is demanding security guarantees from the West, including a promise by NATO never to admit Ukraine. Moscow sees the former Soviet republic as a buffer between Russia and NATO countries.

Several rounds of U.S.-Russia talks over Ukraine have failed to achieve a breakthrough.

On Tuesday, a U.S. plane carrying military equipment and munitions landed in Kyiv, the third installment of a $200 million package to shore up Ukraine's defenses.

Tension appeared to be increasing, with the White House saying the risk of a Russian invasion of Ukraine "remains imminent."

A senior US official laid out economic sanctions "with massive consequences" that go far beyond previous measures implemented in 2014 after Russia invaded Ukraine's Crimea region, according to an AFP report.

New measures would include restrictions on exports of high-tech US equipment in the artificial intelligence, quantum computing and aerospace sectors, the official told reporters on condition of anonymity.

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