KYIV, Ukraine • Underscoring determined U.S. support, Secretary of State Antony Blinken paid an unannounced visit to Kyiv on Thursday and the Biden administration ramped up military aid by more than $2.8 billion to Ukraine and other European countries threatened by Russia.

The new assistance came as the U.S. sought to boost momentum in Ukraine’s counteroffensive against Russia — and amid fears that public support is waning as the war drags on. President Joe Biden, Blinken and Defense Secretary Lloyd Austin all participated in meetings aimed at showing U.S. resolve to stand behind Ukraine.

In Kyiv, Blinken said the administration would provide $2.2 billion in long-term military financing to Ukraine and 18 of its neighbors “potentially at risk of future Russian aggression.” That’s on top of a $675 million package of heavy weaponry, ammunition and armored vehicles for Ukraine alone, announced by Austin and Gen. Mark Milley, chairman of the Joint Chiefs of Staff, earlier in the day.

“I thought it was particularly meaningful (to visit) at this time as Ukraine is starting this counteroffensive in the south, also in the east,” Blinken said in Kyiv before boarding a train for Poland after meeting Ukrainian President Volodomyr Zelensky and his top aides.

“It’s early days, but we’re seeing real effectiveness on the ground, and we’re proud of the fact that our support, the support of so many other countries, is helping to enable what the Ukrainians are doing and working to liberate territory seized by Russia in this aggression,” Blinken said.

He told Zelensky when they met, “We know this is a pivotal moment, more than six months into Russia’s war of aggression against Ukraine, as your counteroffensive is now underway and proving effective.”

Zelensky replied, “We are grateful for the signal, for this enormous support that you’re providing on a day-to-day basis.”

The new funding and military weapons are designed to provide enduring training and support for what Gen. Milley called a “very deliberate” counteroffensive that Ukrainian troops have launched.

Meeting virtually, Biden and the leaders of major U.S. allies all emphasized their countries’ strong support “for Ukraine as it defends itself from Russian aggression,” according to a White House readout.

“Russia’s weaponization of energy” and what to do about it — a major concern for this winter in Europe — was also discussed, said press secretary Karine Jean-Pierre. Those on the call included the leaders of Germany, Italy, the United Kingdom, Poland, Romania, NATO, Canada and Japan and representatives from France and the European Union.

Austin and Milley announced the package of heavy weaponry, ammunition and armored vehicles for Ukraine alone at a conference in Ramstein, Germany.

“We are seeing real and measurable gains from Ukraine in the use of these systems,” said Milley.

He said Russia is suffering significant equipment and troop losses.

But, he added, “The war is not over. Russia is a big country. They have very serious ambitions with respect to Ukraine. So sustainment of Ukraine to continue their fight for their survival will be necessary.”

The $2.2 billion in so-called Foreign Military Financing has already been appropriated by Congress, but lawmakers, some of whom have expressed concerns about the massive amounts of money going to Ukraine, must still approve the actual allotments.

Just two weeks ago, the administration had announced a $3 billion package of support for Ukraine.

About $1 billion of the total will go to Ukraine and the rest will be divided among Albania, Bosnia, Bulgaria, Croatia, the Czech Republic, Estonia, Georgia, Greece, Kosovo, Latvia, Lithuania, Moldova, Montenegro, North Macedonia, Poland, Romania, Slovakia and Slovenia, the State Department said.

It will help those countries “deter and defend against emergent threats to their sovereignty and territorial integrity” by enhancing their military integration with NATO and countering “Russian influence and aggression,” the department said.

Secretary of State Antony Blinken stands near a damaged residential building Thursday during his visit to the city of Irpin, Ukraine.

The Associated Press