Will decision to give jets to US for expected transfer to Ukrainian forces make a significant difference to war with Russia?
Is Ukraine getting extra fighter jets from Poland?
Ukraine's armed forces are in dire need of fighter jets to help the country fight off Russian aggression. Its air force, though still flying, is outnumbered by its rival.
However, any new aircraft must have Ukrainian pilots trained to use it. This means that they must be Russian-made aircraft, primarily MiG-29 fighters. Some still have MiGs in fleets of Eastern European countries which, a week ago, the EU said it hoped could be delivered to Ukraine.
Poland said on Tuesday evening that it was ready to hand over its fleet of 28 MiG-29s to the US - in exchange for which they are expected to hand over to the Ukrainian Air Force. The Pentagon has said the deal is "not sustainable", though a senior State Department official said they would see how to respond to the proposal. Poland was expecting the US to supply more advanced F-16s to make up for the shortfall.
Is Poland in danger from Russia's retaliation?
Western countries are supplying Ukraine with increasingly sophisticated weapons to fight the Russian advance. Anti-tank and anti-aircraft missiles supplied so far have troubled Russia, but there has been no direct retaliation against any of the countries involved.
Giving Ukraine faster jets is clearly a move, and Poland is nervous enough about the Kremlin's response to using the US as an intermediary to help Kyiv get fighter planes , although the maneuver is hardly subtle.
The Russian Defense Ministry has warned that if warplanes based in another country strike Russian targets, it "could be construed as involvement of those countries in a military conflict". But if the US is transferring fighters to Ukraine, Russia may not want to directly engage the Americans.
It is still considered unlikely that Russia would want to retaliate militarily against Poland, on the grounds that it is a member of NATO. But Russia may consider other actions against Warsaw, perhaps special economic sanctions.
Will the extra jets make a significant difference to the war?
Despite a spirited defense by Ukraine of its territory and anti-tank and anti-air weapons already supplied by the West, Russia's advance is on the ground, albeit with more than expected losses of troops and material.
If the Ukrainian Air Force had had further losses, it would soon have reached the point where it would be unable to defend itself from attack in the skies. A new fleet of aircraft will ensure that the airspace over Ukraine is fought at least for a time, and will make Russia think twice about air strikes on Kyiv.
But the main problem currently facing the Armed Forces of Ukraine is Russia's predominance of artillery. Russia has been shelling cities such as Kharkiv and Mariupol for several days in an attempt to force them to surrender.
Ukraine could try to use its planes to strike enemy convoys from the air, but that would be risky as Russia is believed to have brought air defense systems closer to the front lines in the past few days.