Hiroshima, May 20 : US National Security Adviser (NSA) Jake Sullivan said that Washington will back providing advanced fighter jets, including F-16s, to Ukraine, as well as train pilots in the war-torn nation on how to fly them. Addressing a press conference here on Friday, Sullivan said that President Joe Biden "informed his G7 counterparts" of the move at the bloc's summit in in the Japanese city earlier in the day, the BBC reported. "Over the past few months, we and our allies and partners have really focussed on providing Ukraine with the systems weapon and training it needs to conduct offensive operations this spring and summer. We have delivered what we promised. "Now we have turned to discussions about improving the Ukrainian air force as part of our long-term commitment to Ukraine's self-defence. As the training unfolds in the coming months, we will work with our allies to determine when planes will be delivered, who will be delivering them, and how many," the BBC quoted the NSA as saying. Ukraine has repeatedly lobbied its Western allies to provide jets to help in its fight against Russia. Ukrainian President Volodymyr Zelensky has welcomed what he described as a "historic decision", adding that he looked forward to "discussing the practical implementation" of the plan at the G7 summit in Hiroshima, where he will arrive on Sunday. The development comes months after Biden had said in February that he was "ruling out for now" sending advanced fighters to Ukraine. But during Friday's press conference, Sullivan told reporters that US had provided weapons to Kiev as they were needed on the battlefield, and the decision to start supplying advanced fighters to Ukraine indicated the conflict had entered a new phase, reports the BBC. "Now we have delivered everything we said we were going to deliver, so we put the Ukrainians in a position to make progress on the battlefield through the counter-offensive. "We've reached a moment where it is time to look down the road, and say what is Ukraine going to need as part of a future force to defend against Russian aggression," he said. Meanwhile, the UK, Netherlands, Belgium and Denmark have also welcomed Washington's move. UK Prime Minister Rishi Sunak tweeted: "The UK will work together with the USA and the Netherlands, Belgium and Denmark to get Ukraine the combat air capability it needs." The UK does not have any F-16s in its air force itself. Denmark has also announced that it will now be able to support the training of pilots, but did not confirm whether it would send any jets to Ukraine. Denmark's air force has 40 F-16s, around 30 of which are operational. When Russia launched its full-scale invasion on February 24, 2022, Ukraine was believed to have around 120 combat capable aircraft -- mainly consisting of aging Soviet-era MiG-29s and Su-27s. But officials say they need up to 200 jets to match Moscow's air-power -- which is thought to be five or six times greater than Kiev's. Earlier this year, some Eastern European nations had sent Soviet-era Mig fighter jets to Ukraine. /IANS