I rather suspect what would also occur would be (a) in the USA Republicans would deny the UFO existed and explain it's all a communist-democrat-gun-hater plot to take away people's bibles and guns, (b) Brexit Boris would tell the UK the UFO was a clear demonstration of how galaxy-wide trading was going to make Britain great again, (c) in China Xi would add to his Thoughts to proclaim that UFOs with Chinese characteristics were the consequence of the Communist Party's benign and wise rule, while in Russia a small group of Kremlin-sponsored hackers would be trying to upload socially divisive memes to the UFO's command systems in the hope of using the surface of the vessel as a huge social media display board that would further undermine what remains of the West and thereby help Putin to make Russia seem fractionally less awful by comparison.

After some time, the UFO would disappear and no one would notice.