"Slovakia delivers first 4 MIG-29 jets to Ukraine"
Predictable tbh. There's a pretty decent chance that the previous ruling party will return back to power later this year and they've been increasingly against providing military help to Ukraine. The guys currently in charge looked at the polls, realized what's most likely going to happen, and so simply gave Ukraine everything we conceivably could give them like this while they're still in power, knowing that more jets from more countries will inevitably follow after this now that the line was crossed.
Tbh, I wouldn't be surprised if the US Democrats decided to do something similar given that they are quite likely to lose the next presidential election, if the war is still raging by then. The Republicans are getting quite tired of financing Ukrainian war effort so, I'd honestly expect that, while watching the polls spelling their inevitable electoral defeat in a few months, Biden and co. will simply say fuck it and send about half their entire military arsenal to Ukraine at once

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I dont know if this is correct but some general dude on youtube said Russia has the most advanced air defence systems at the moment.
If that claim is true then why send some few jets to Ukraine? They would have to send thousands to make an impact. Just asking for a friend.
They've been really hyping up S-500 all the while as it was being developed, claiming that it's generations ahead of anything any other country has and that it makes Russia's airspace invulnerable, but, so far, it has never really been tested in actual combat. S-400
has scored some hits on Ukrainian Air Force, but it's quite clearly much weaker than advertised. It's apparently been
defeated multiple times by drone swarms, which Ukrainians shouldn't have too much trouble doing as well.