The threat arises from the fact that Washington has taught each country to have no trust in America's veracity. The governments of the four countries have learned that everything Washington says is a lie.
Moreover, the countries have learned that Washington does not accept their sovereignty and objects to their existence. Each of the four countries has experienced sanctions designed to overthrow their governments or cause them to submit to Washington's will.
Russia long ago saw through Washington's disingenuous claim that the missile ring that Washington has arrayed around Russia is defensive and directed against (non-existent) Iranian missiles. Putin has said many times that the "defensive" missiles can easily and quickly be converted into nuclear armed offensive missiles that leave Russia no response time. I have always been amazed at the utter stupidity of the Polish and Romanian governments for accepting these American missiles. No doubt the Polish and Romanian officials were paid handsome bribes, but money is no good to a dead person. You can bet your life that the Russians are not going to permit such operable weapons to be on Russian borders during a time of high tensions that exists today between the West and Russia.