"We're going to talk," Biden told reporters, speaking the morning after he answered with an emphatic "no" when asked at the White House whether he favored sending F-16 fighter jets to Ukraine.

The United States is by far the biggest supplier of weapons to Ukraine, where the Russian invasion is now approaching the one-year mark. A coalition of other Western countries is also sending arms, ranging from rifles to armored vehicles and artillery.

However, with Russia showing no sign of letting up in its pulverizing of neighbor Ukraine, Zelensky has been issuing calls for ever more powerful and sophisticated weapons.

Most recently, the United States and Germany agreed to send advanced tanks, following the earlier lead of Britain.

Now, Ukraine is pressuring for fighter jets and long-range missiles that could hit Russian targets far behind the front lines.

On Tuesday, Polish deputy defense minister Wojciech Skurkiewicz told AFP that Poland, a key player in the Western coalition, is not currently having "official discussions" on transferring any of its own F-16s to Ukraine.