Fighters will boost Ukrainian air defences as soldiers face tough battles against Russians on eastern front lines.

The pilots will be brought to the US in September where they will first learn English before starting their training on how to fly the advanced fighter.

Speaking in Washington, DC, on Thursday, Pentagon spokesman Pat Ryder said the training in Texas and Arizona would involve “several” pilots and “dozens” of personnel to maintain the aircraft.

US President Joe Biden and his Ukrainian counterpart Volodymyr Zelenskyy discussed the training programme in a call on Thursday, the White House said.

“President Biden reiterated the US commitment to support Ukraine’s defence against Russian aggression for as long as it takes, and to hold Russia accountable for its actions,” it said in a statement.

The US announcement expands plans by European allies Denmark and the Netherlands to donate F-16 fighters to Ukraine and train its pilots. Norway has also said it will provide the planes to Ukraine with Greece joining the countries offering training.

Speaking in an interview with Jordan’s Al-Mamlaka public service TV news channel, meanwhile, Chairman of the Joint Chiefs of Staff Mark Milley said Ukraine was likely to receive the planes “in the not-too-distant future”, saying they would strengthen Ukraine’s air defences and bolster its counteroffensive against Russian forces in the country’s east.

Milley noted Ukrainian troops were faced with Russian reinforcements that had many months to prepare minefields, tank ditches and dragon’s teeth tank obstacles “in a very complex set of defensive preparations that the Ukrainians are fighting through …

“The Ukrainians have a significant amount of combat power remaining; this is not over yet,” he said.

“Clearly it’s had partial success to date,” Milley added in the interview in Amman, adding that the speed was slower than the planners had thought.

Ukrainian forces were being trained intensively in various parts of Europe on “command and control of offensive formations and combined arms manoeuvre and to break complex obstacles that will bolster its capabilities,” the four-star US Army general said.

“Again, it’s bloody, it’s long and it’s slow. And we had predicted that several months ago,” he said.

It is likely to be some months before Ukraine will be able to feel the benefit of the new fighter jets.

Ryder said training on the F-16s was likely to last between five and eight months, depending on the pilots’ existing skills.

Language training at the beginning was crucial, “given the complexities and the specialised English that’s required to fly these aircraft,” he said.