I've never said Biden caused the war in Ukraine. Putin felt comfortable invading during Biden's tenure. Why do you think that is?
Because Trump had spent years weakening NATO and so Putin figured they wouldn't push back.
Also, due to domestic issues in Russia that began to become a bigger problem in 2020.
Also, he felt he was making significant progress in squeezing Ukraine without military force with Trump's support, so no need to waste resources.
And, finally, Zelensky had started cracking down on Russian propaganda in Ukraine and said he was going to support the National Defense plan that called for a stronger position on the Crimea situation.
Putin didn't start building up his troops until then.
The situation was just different in 2021 than it had been earlier.
North Korea did indeed test missiles after meeting with Trump but the tests were few and were mostly short range type. Many nations test short range as part of their military defence complex.
Just for fun, why don't you look up at how many tests have been carried out during Biden's tenure and how many were mid to long range (ICMB). I think you will be surprised...if not scared. Why do you think that is?
Because North Korea has been expanding their production and have more of them to test now.
They started testing ICBMs under Trump, and have been expanding their tests ever since.