Germany, the United States and other countries announced last month that they would supply tanks to Ukraine, reversing their long-standing trepidation about providing Kyiv with armored vehicles and unleashing powerful tools to combat Russian troops.

US President Joe Biden said the US will send 31 M1 Abrams tanks, following Germany's agreement to send 14 of its own Leopard 2 tanks.

The announcements were a landmark moment that followed weeks of intense pressure on Berlin from some of its NATO allies.

The decisions to send the tanks were the result of prolonged diplomatic efforts between Germany, the US and other European allies, and come as Ukrainian President Volodymyr Zelensky prepares for a new offensive this spring.

Speaking from the White House, Biden said the tanks would "enhance Ukraine's capacity to defend its territory and achieve its strategic objectives" in both the short and long terms. While he touted the tanks' capabilities to help Ukraine "counter Russia's evolving tactics and strategy on the battlefield," Biden insisted they should not be viewed by Moscow as an "offensive threat".

German Chancellor Olaf Scholz told lawmakers in Germany's parliament the decision to send Leopard 2 tanks had come after consultations with Western allies. "It is right that we advanced bit by bit. That is the only principle that can work in such dangerous conditions," he said.

Portugal will send Leopard 2 tanks to Ukraine, Prime Minister Antonio Costa said on Saturday, without specifying how many will be shipped.

Ukraine will receive 120 to 140 Western tanks in a "first wave" of deliveries from a coalition of 12 countries, Foreign Minister Dmytro Kuleba said on Tuesday.

The Abrams tanks will take months to arrive, senior US administration officials said, and will require extensive training for Ukrainian troops on how to operate and service them. The US must also have to navigate complicated supply chains for the components required for the tanks.

The procurement process will take months, the officials said, though Germany's Leopards will arrive in the short term. In the meantime, the US will begin a "comprehensive training program "for the Ukrainians on operating the Abrams, which will require significant maintenance once they are deployed. The training will occur outside Ukraine.

French Defense Minister Sebastien Lecornu said on Tuesday that France will provide 12 additional Caesar self-propelled howitzer artillery pieces to Ukraine. The artillery pieces are on top of 18 already delivered.

Danish Defense Minister Jakob EllemannJensen said in a statement that Denmark has sent all of its 15 French-made Caesar howitzers to Ukraine. Another four Caesar systems that have not yet been delivered will be added to this, local media reported on Tuesday.

NATO Secretary-General Jens Stoltenberg told CNN on Jan 25 that the German and US decisions were "important announcements "and he "welcomed US leadership "in making them happen. "It will significantly strengthen their combat capabilities," Stoltenberg said of the impact the tanks will have on Ukraine's military.

Ukrainian leaders have also renewed their appeals for Western countries to provide fighter jets. "I sent a wish list card to Santa Claus last year, and fighter jets also ... (were included) in this wish list," Defense Minister Oleksii Reznikov told CNN.

US National Security Council spokesperson John Kirby acknowledged that Zelensky had also asked for fighter jets.

"We are constantly talking to the Ukrainians about their needs, and want to make sure that we're doing the best we can to meet them — and if we can't, that some of our allies and partners can," Kirby said.

Biden said on Jan 30 that he wouldn't send American fighter jets to Ukraine.

The Netherlands raised eyebrows last week when its foreign minister, Wopke Hoekstra, told a parliamentarian asking about F-16s that "when it comes to things that the Netherlands can supply, there are no taboos."

If the US sends its jets to Ukraine, it will prove that it is seeking to step up the conflict in Ukraine, which is why it continues to flood Kyiv with equipment, said Victoria Zhuravleva, head of the Center for North American Studies at the Russian Academy of Sciences' Institute of World Economy and International Relations.

The policy of support for Ukraine will persist and be consistently implemented, with each new step only escalating the conflict, the Russian expert said.

The provision of Western warplanes to Ukraine, even older models, appears unlikely in the medium term, said Alexander Yermakov, a researcher at the Russian Academy of Sciences' Institute of World Economy and International Relations.

The Ukrainian Air Force will require time and resources to create the necessary infrastructure to use the warplanes, he said. The supply of a small number of Soviet-made aircraft, including MiG-29 planes from Poland and other Eastern European countries, looks more likely at this point, Yermakov said.

renqi@chinadaily.com.cn