President Joe Biden snuck into Kyiv on Monday for the first visit since Russia started a full-scale invasion of Ukraine over a year ago, proving in a spectacular manner his personal devotion to the country and its fight as the war enters a new phase of uncertainty.

Air raid sirens could be heard wailing around Kyiv as President Biden and Ukrainian President Volodymyr Zelensky walked around the golden-domed St. Michael's Cathedral. The visit comes at a critical time in the 12-month conflict, with Russia preparing for an expected spring offensive and Ukraine hoping to soon retake territory.

Biden pledged a half-billion dollars in extra support, stating that the package would include more military weapons like ammunition for artillery, javelins, and howitzers, USA Today reported. In addition, he stated that Russia would face further penalties later this week.

The United States and other Western nations have sent weapons, tanks, and ammunition to Ukraine in an effort to alter the course of the conflict. Biden is providing a distinct picture of American support for Zelensky by making a personal visit. Zelensky has spent the past year working to mobilize the globe behind his country and begging for increased amounts of help.

NBC News said that, after a lengthy, secret flight from Washington, Biden landed in Kyiv at 8 a.m. local time and arrived at the Mariinsky Palace half an hour later. He left Kyiv early in the afternoon.

American officials have quietly expressed confidence that the enormous supply of weapons to Ukraine, which includes modern vehicles, longer-range missiles, and Patriot air defense systems, will help the country succeed on the battlefield and strengthen Zelensky's position to negotiate an end to the war.

Nevertheless, it is still unknown what boundaries Zelensky could be ready to accept in peace discussions, and the United States has consistently refused to describe what a solution might include beyond declaring that Zelensky will decide.

Biden's visit was extremely significant, occurring a day before a planned address by Russian President Vladimir Putin commemorating the war's anniversary. Biden claimed from Kyiv that Putin's "war of conquest is failing."

A person familiar with the situation told CNN that Biden was offered a variety of choices for a visit to Ukraine but concluded that a trip to Kyiv made the most sense. Although Biden was informed over the course of many months on the planning for a prospective trip to Ukraine, the source reported that Biden only expressed concern about the risk of a trip to Ukraine once. Still, that concern was for the safety of others rather than his own. Other authorities were plainly exceedingly anxious for Biden's safety, and a number of security contingency plans were developed.

Before departing, Biden had dinner with his wife in Washington on Saturday evening. He was not seen in public again until Monday morning, when he arrived in Kyiv.