Okay. Poland is a member of NATO. The North Atlantic Treaty Organization. If Russia nuked Poland, or attacked it in any way, all of NATO, by treaty obligation, would rush to Poland's defense, and thus would be obligated to declare war on Russia. That would mean Russia would simultaneously be at war with the following nations:
Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, The Netherlands, Norway, Portugal, The United Kingdom, The United States, Greece, Turkey, Germany, Spain, The Czech Republic, Hungary, Poland, Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia.
Russia doesn't have the resources to combat 26 different nations all at once. Nor are they willing to wage war on all those nations.
Serio is safe. God Bless NATO.