VP Kamala Harris heads to Poland amid Nato fighter jet rift

US Vice-President Kamala Harris has departed for Poland and Romania, giving the second-ranking US official a chance to negotiate directly with Polish leaders on the issue of fighter jet transfers to Ukraine. The topic has exposed disagreements within the Nato alliance, as the Polish government's public offer on Tuesday to provide the US with MiG-29 fighter jets as an intermediary step toward transferring them to Ukraine was rejected as "not tenable" by American officials.

In advance of the vice-president's trip, a senior US administration official said the topic of Polish jets would "absolutely" come up during her meetings with Polish leaders - but was non-committal on where the talks would go.

"We have been in dialogue with the Poles for some time about how best to provide a variety of security assistance to Ukraine," the official said. "A number of people have had a variety of ideas, and we think all of them are worth discussing."

Ukrainian President Volodymyr Zelensky has been pressing the Nato military alliance for the Soviet-era jets - which its fighter pilots know how to operate - to bolster its defence against the two-week-old Russian invasion. He mentioned jets in a speech to US members of Congress last week and again when addressing the British Parliament on Tuesday.

"It's been 13 days we've been hearing promises, 13 days we've been told we'll be helped in the air, that there will be planes," he told British lawmakers.

While Nato leaders, including US Secretary of State Antony Blinken, have expressed openness to the idea, arranging the details of such a transfer without risking a confrontation between Nato and Russian forces has proven difficult.

"Poland's proposal shows there are some complexities that the issue presents," Mr Blinken said in a press conference with British Foreign Secretary Elizabeth Truss on Wednesday. "We have to make sure we're doing it in the right way."

Russia, Nato officials worry, could view Ukrainian-piloted fighter jets taking off from a Nato nation - whether it is Poland or a US base in Germany - and heading into combat as a belligerent act on the part of the western alliance. There are also concerns that, in the face of sustained Russian attacks, Ukraine is running out of operating airfields on its own territory.

Negotiations among Nato allies were being conducted behind closed doors, but on Tuesday Poland made a public offer to transfer its MiG-29 jets to the Ramstein US air base in Germany, in exchange for US made aircraft of similar condition and sophistication.

According to US Undersecretary of State for Political Affairs Victoria Nuland, who was testifying before a US Congress committee at the time of the announcement, the US did not have any advance knowledge of Poland's public offer.

In a statement released on Tuesday evening, Pentagon press secretary John Kirby described Poland's offer as presenting "difficult logistical challenges".

"The prospect of fighter jets 'at the disposal of the Government of the United States of America' departing from a US/Nato base in Germany to fly into airspace that is contested with Russia over Ukraine raises serious concerns for the entire Nato alliance," he said.

A German government spokesperson was more emphatic on Wednesday, saying that a transfer of Polish fighters to Ukraine "was not currently on the table".

American officials have repeatedly emphasised the US position that the decision on fighters was ultimately one for the Polish government to make, suggesting that the US - at least publicly - may want to stay out of direct involvement in supplying Ukraine with jets.

Polish leaders, however, have said that their nation would only act in co-ordination with allies.

"It cannot be that Poland, as the only Nato country, has to bear the risk, and other countries would not have to do anything about it or compensate us or share it with us," Deputy Foreign Minister Pawel Jablonski said on Polish Radio on Wednesday.

Other forms of US military assistance to Ukraine is ongoing. On Tuesday evening, US congressional leaders reached an agreement to provide an additional $7bn (£5.3bn) in military hardware to Ukraine and US allies in the region, indicating that more weapons are in the pipeline.

"We have provided extraordinary support to Ukraine," Mr Blinken said on Wednsesday. "Support that has been used extremely effectively by Ukrainian defenders."