Ukrainian President Volodymyr Zelensky confirmed early Wednesday that he is en route to Washington to meet with President Biden and address Congress. It is first trip outside Ukraine since Russia invaded 300 days ago. 

Zelensky’s brief trip to Washington will include an Oval Office meeting with Biden, a joint press conference, and an address to a joint session of Congress, which is currently considering a massive spending bill with $44.9 billion in aid for Ukraine. A U.S. official said Zelensky’s surprise visit will help build “momentum” for the additional assistance. 

Biden will also use Zelensky’s visit to announce a $1.9 billion military aid package that includes a Patriot missile battery, America’s most advanced air defense weapon and a top priority for Ukraine, a senior administration official told reporters in a background briefing. The package will also reportedly include Joint Direct Attack Munitions kits (JDAMs), which turn “dumb” bombs into precision-guided missiles, and more artillery shells, trucks, and rockets for the High Mobility Artillery Rocket System (HIMAR) and HARM air-to-surface anti-radiation missile system, AP reports. 

CNN explains how those weapons could help Ukraine defend itself against Russia 

The Biden administration was reluctant to give Ukraine Patriot missiles, but Russia’s “devastating destruction of the country’s civilian infrastructure, including loss of electricity and heat during winter, ultimately overcame U.S. reservations,” The Associated Press reports. Patriot missiles should help Kyiv shoot down Russian ballistic missiles and attack aircraft. Kremlin spokesman Dmitry Peskov said Wednesday that with the “range of supplied weapons” expanding, “all this leads to an aggravation of the conflict and does not bode well for Ukraine.” 

A Patriot battery typically includes up to eight launchers that can each hold four missiles plus a phased array radar, control station, computers, and generators. It requires about 90 soldiers to operate and maintain, AP notes, but only three are needed to fire it. The U.S. will train Ukrainian soldiers to operate the Patriot battery in Germany.

Zelensky’s visit “will symbolically bolster America’s role as the arsenal of democracy in the bitter war for Ukraine’s survival,” Stephen Collinson writes at CNN, and “draw poignant echoes of British Prime Minister Winston Churchill’s arrival in Washington, 81 years ago on Thursday, days after the Japanese attack on Pearl Harbor.” 

Zelensky said he will bring Biden and Congress a Ukrainian flag signed by frontline troops defending the besieged city of Bakhmut, which Zelensky visited Monday.