White House has warned the Kremlin about Biden's visit to Ukraine

Before U.S. President Joe Biden's visit to Kyiv, Washington contacted Russia to avoid a direct conflict between the two nuclear-armed countries.

The Associated Press reported this with reference to the White House.

"The White House will not go into details, but National Security Adviser Jake Sullivan said he notified Moscow of Biden's visit to Kyiv shortly before he left Washington to avoid any miscalculations that could lead to a direct conflict between the two nuclear powers," the report said.

At the same time, the airspace over Kyiv at the time of the visit was monitored by American E-3 Sentry and RC-135W Rivet Joint aircraft, which were stationed in Poland.

Nevertheless, during Biden's meeting with President Volodymyr Zelensky, an air alert was declared in Ukraine. The heads of state and the delegations accompanying them left St. Michael's Cathedral to the sound of sirens.

Biden arrived in Kyiv for the first time since the beginning of Russia's invasion of Ukraine, four days before the anniversary of the invasion.

During the visit, the US president made a number of statements. He announced the transfer to Ukraine of 700 tanks, thousands of armored vehicles, and a thousand artillery systems from the United States and partner countries. Biden also said that this week the United States would announce additional sanctions against the Russian elite and companies that try to evade existing restrictions and "support the Russian war machine."

After the speech, the American leader left Ukraine. He headed to Poland, where he plans to meet with President Andrzej Duda and leaders of other Ukraine's allies.

Zelensky called Biden's visit to Kyiv the most important in the history of Ukrainian-American relations.