Putin also spoke with Alexander Lukashenko, leader of Ukraine's northern neighbor Belarus, which is engaged in major joint military drills with Russia.

After Macron's call with Putin, a French presidency official said there were no indications from what Putin told Macron that Russia is preparing an offensive against Ukraine.

"We are nevertheless extremely vigilant and alert to the Russian (military) posture in order to avoid the worst," the French official said.

Russia said on Saturday that it had decided to "optimize" its diplomatic staff numbers in Ukraine, fearing "provocations" by Kyiv or others. It said its embassy and consulates in Ukraine continued to perform their key functions.

A U.S. official on Saturday said there was no telling what Putin has decided, but that the steps Russia is taking "in plain sight" make them fear the worst.

ZELENSKIY CALLS FOR CALM

Biden told Putin during their call that the United States is pushing for diplomacy but ready for "other scenarios," the White House said.

In Kyiv, several thousand Ukrainians filed through the center of the city, chanting "Glory to Ukraine" and carrying banners that said "Ukrainians will resist" and "invaders must die."

Zelenskiy, who attended police drills in the southern Kherson region, echoed Washington's assessment that a Russian attack could happen at any time, but stressed that it was important for Ukrainians to remain calm.

"The best friend of our enemies is panic in our country," he said.

Putin, jostling for influence in post-Cold War Europe, is seeking security guarantees from Biden to block Kyiv's entry into NATO and missile deployments near Russia's borders.

Washington regards many of the proposals as non-starters but has pushed the Kremlin to discuss them jointly with Washington and its European allies.

Moscow has repeatedly disputed Washington's version of events, saying it has massed the troops near the Ukrainian border to maintain its own security against aggression by NATO allies.

Also on Saturday, the Russian military said it had used "appropriate means" to make a U.S. submarine depart from Russian waters in the far east after the vessel ignored a Russian order to surface, Interfax news agency reported.

The submarine was detected in Russian waters as elements of Russia's Pacific Fleet conducted naval exercises near the Kuril islands, the defence ministry was quoted as saying.

In a statement, a U.S. military spokesman denied it had carried out operations in Russian territorial waters.

(Reporting by Trevor Hunnicutt, Idrees Ali, Simon Lewis, Vladimir Soldatkin, Pavel Polityuk, Valentyn Ogirenko, Dmitry Antonov, Leigh Thomas, Mike Stone, Makini Brice and Humeyra Pamuk; Writing by Trevor Hunnicutt and Frances Kerry, Editing by Angus MacSwan and Daniel Wallis)