MOSCOW — The Russian military on Friday announced massive drills of its strategic nuclear forces, a stark reminder of the country’s nuclear might amid Western fears that Moscow might be preparing to invade Ukraine.

Russian President Vladimir Putin will personally oversee Saturday’s exercise, which will involve multiple practice launches of intercontinental ballistic missiles and cruise missiles, the Defense Ministry said.

Kremlin spokesman Dmitry Peskov said Putin would observe the drills from the Defense Ministry’s situation room and supervise the practice missile launches himself.

The ministry said it planned the maneuvers some time ago to check the readiness of Russia’s military command and personnel, as well as the reliability of its nuclear and conventional weapons.

The war games follow U.S. President Joe Biden’s warning on Thursday that Russia could invade Ukraine within days.

Western fears focus on an estimated 150,000 Russian troops — including about 60% of Russia’s overall ground forces — concentrated near Ukraine’s borders. The Kremlin insists it has no plans to invade.

But Moscow has demanded that the U.S. and its allies keep Ukraine and other ex-Soviet nations out of NATO, not deploy weapons in Ukraine and pull back NATO forces from Eastern Europe.

Washington and its allies bluntly rejected the Russian demands, and Moscow threatened to take unspecified “military-technical measures” if the West continued to stonewall.

Russia holds massive drills of its strategic nuclear forces on an annual basis, but the maneuvers planned for Saturday pointedly involve the Black Sea Fleet. The fleet is based on the Crimean Peninsula, which Russia annexed from Ukraine in 2014.

The Black Sea Fleet has surface warships and submarines equipped with Kalibr cruise missiles, but its doesn’t have intercontinental ballistic missiles and didn’t take part in similar previous drills of the country’s strategic forces.

In the past, Russia has held the annual strategic forces drills in the fall. U.S. officials have voiced concern that Moscow shifted the exercise to February to coincide with a possible invasion of Ukraine.

The Kremlin’s Peskov said Russia notified foreign partners about the maneuvers in advance, adding that the exercise shouldn’t cause worries in the West.

“Practice launches of ballistic missiles are part of regular training,” he said. “They are preceded by a series of notices to other nations via different channels.”

Putin met with Belarusian President Alexander Lukashenko and invited him to watch Saturday’s maneuvers.

The authoritarian Lukashenko, who has edged closer to Moscow amid Western sanctions for his crackdown on domestic protests, has offered to host Russian nuclear weapons. in Belarus, which neighbors Ukraine to the north.

The strategic forces of both Russia and the United States include a nuclear triad of land-based intercontinental ballistic missiles, submarine-based ICBMs and nuclear-capable bombers.

The exercise of Russia’s nuclear forces follows a series of sweeping drills that the Russian military held near Ukraine and in Belarus.

The Russian military said it started pulling some of troops massed near Ukraine back to their permanent bases after the drills. The U.S. and its allies questioned the claim and said that Moscow has actually moved thousands of new troops closer to Ukraine.

Moscow argued that the pullback takes time and rejected Western criticism, saying that it would deploy troops wherever it’s necessary to ensure national security.