MOSCOW -- Russia's top diplomat angrily rejected U.S. allegations that Moscow was preparing a pretext to invade Ukraine, as Russian troops that are amassed near the Ukraine border launched more drills Monday.

The White House said Friday that U.S. intelligence officials had concluded that Russia had already deployed operatives to rebel-controlled eastern Ukraine to carry out acts of sabotage there and blame them on Ukraine in a 鈥渇alse-flag operation鈥 to create a pretext for possible invasion.

Speaking to reporters Monday, Russian Foreign Minister Sergey Lavrov dismissed the U.S. claim as 鈥渢otal disinformation.鈥

He reaffirmed that Russia expects a written response this week from the U.S. and its allies to Moscow's request for binding guarantees that NATO will not embrace Ukraine or any other ex-Soviet nations, or station its forces and weapons there.

Washington and its allies firmly rejected Moscow's demands during last week's Russia-U.S. negotiations in Geneva and a related NATO-Russia meeting in Brussels, which were held as an estimated 100,000 Russian troops with tanks and other heavy weapons are massed near Ukraine in what the West fears might be a prelude to an invasion.

Amid the troops buildup, Russia in recent weeks has held a series of war games in regions that border Ukraine. On Monday, the military announced the launch of another exercise involving armored units stationed in the western part of Russia that includes 300 combat vehicles.

A delegation of U.S. senators is visiting Ukraine to emphasize U.S. support for the country.

鈥淥ur bipartisan congressional delegation sends a clear message to the global community: the United States stands in unwavering support of our Ukrainian partners to defend their sovereignty and in the face of persistent Russian aggression,鈥 Sen. Jeanne Shaheen, a New Hampshire Democrat, said in a statement.

Sen. Richard Blumenthal, a Connecticut Democrat, said after the delegation met with President Volodymyr Zelenskyy that if Russia invades Ukraine 鈥渨e will impose crippling economic sanctions, but more important we will give the people of Ukraine the arms, lethal arms they need to defend their lives and livelihoods.鈥

Speaking Monday on a visit to Kyiv, German Foreign Minister Annalena Baerbock warned that 鈥渁ny further escalation would carry a high price for the Russian regime - economic, political and strategic鈥 - and emphasized the need to continue negotiations.

鈥淲e are prepared to have a serious dialogue with Russia, because diplomacy is the only way to defuse this highly dangerous situation,鈥 she said.

Baerbock said Germany has offered to send cybersecurity specialists to Ukraine to help investigate last week's cyberattacks, which Ukrainian authorities have blamed on Russia. At the same time, she noted that Germany hasn't changed its refusal to provide it with weapons.

鈥淲e made clear that we will do everything to avoid escalating the crisis,鈥 she said.

German Chancellor Olaf Scholz said on a visit to Spain that 鈥渨e expect clear steps from Russia to deescalate the situation,鈥 adding that 鈥渕ilitary aggression against Ukraine would entail serious political and economic consequences.鈥

Ukrainian officials have warned that Russia could launch an attack from various directions, including from the territory of its ally Belarus.

Belarusian President Alexander Lukashenko, who has increasingly relied on the Kremlin's support amid Western sanctions over a brutal crackdown on domestic protests, said Russia and Belarus will hold massive military drills next month.

Lukashenko said the maneuvers will be conducted on Belarus' western border and also in the country's south, where it borders Ukraine. Belarus Security Council Secretary Alexander Volfovich said Monday that Russian troops already had started arriving in the country for the exercise, according to the BELTA news agency.

Russia has denied having plans to attack its neighbor and in turn accused the Ukrainian leadership of hatching plans to use force to reclaim control of Russian-backed rebel-held territories in eastern Ukraine. Ukrainian authorities have denied it.

Russia annexed the Crimean Peninsula from Ukraine in 2014 after the ouster of Ukraine's Moscow-friendly leader and also threw its weight behind a separatist insurgency in eastern Ukraine. More than 14,000 people have been killed in nearly eight years of fighting there.

Russian President Vladimir Putin has warned that Moscow will take unspecified 鈥渕ilitary-technical measures鈥 if the West stonewalls its demands.

Deputy Foreign Minister Sergei Ryabkov, who led the Russian delegation at the talks with the U.S. in Geneva, said last week that he would 鈥渘either confirm nor exclude鈥 the possibility of Russia sending military assets to Cuba and Venezuela if the U.S. and its allies don't curtail their military activities on Russia's doorstep. U.S. national security adviser Jake Sullivan has dismissed the comments as bluster.

Asked Monday about the possibility of Russian missile deployment to Cuba and Venezuela, Kremlin spokesman Dmitry Peskov told reporters that 鈥淩ussia is thinking about how to ensure its security in the context of the current situation.鈥

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Yuras Karmanau reported from Kyiv, Ukraine. Frank Jordans in Berlin and Aritz Parra in Madrid contributed to this report.