Invasion of the Ukraine: What now Mr. President? Franklin D. Roosevelt or Neville Chamberlain?

The recent news that Russian troops – on vacation from Russia according to Mr. Putins and the separatists fairy tale interpretation – have invaded other parts of the Ukraine and taking hold of Nowoasowsk a city at sea of Asov and aiming to conquer Mariupol . Now the US commander in chief has to decide what to do after weeks and months of unworthy diplomatic maneuvering to find a peaceful solution of the conflict with Russia.
He has now to face two alternatives. He could back down and leave the Ukraine to its own and to Russia’s mercy and accept that the US together with its Nato allies has overextended its reach, when tempting to draw the Ukraine into the Western orbit, or, he has to make a tough choice to intervene by lending much more military support from the US and Nato member countries to the current Ukrainian government to bring down the Russian invasion of the Ukraine.
Neville Chamberlain , the British prime minister, backed down when faced with this challenging decision trying to keep peace with Hitler by signing the Munich Agreement and leaving Czechoslovakia to the mercy of the Nazi regime.
Franklin Delano Roosevelt decided to declare war on Japan and Germany on December 7 in 1941 after the attack on Pearl Harbor. Even Roosevelt preferred to postpone taking military action until then and letting Hitler conquer half of Europe first and let Japan occupy large parts of Asia. The willingness of the American people to fights other peoples war was not very commanding then and now.
However, it would be the final step to accept the current Russian invasion of the Ukraine by the US,, to make it obvious to the whole world, that the US as a global superpower has vanished in history. US global aspirations to maintain a Pax Americana has crumbled away already over the past decades starting with the Korean war, going on to the war in Vietnam and ending in the failure to establish a regime in Iraq and Afghanistan after occupying the countries with his Allies.
Without a credible threat to all other powers in particular Russia in Europe and China in Asia to deny those two global rivals any major success in extending their military, political and economic control on their neighboring countries, the support for the US in Nato and Seato will come to a crushing collapse.
Even in the time of the cold war German governments continuously asked themselves if the US guarantee to defend Germany in case of a Russian invasion was credible. The uprising of 1953 in East Germany , the Hungarian Revolution of 1956 , the building of the Berlin Wall in 1961, the occupation of Czechoslovakia by the Warsaw pact countries in 1968 always ended with a situation that the US did not react to support those peoples.
So there is a long tradition of US foreign policy in particular in Europe to not engage in direct military confrontation with Russia. Will it be like this with the Ukraine again?
It is a bifurcation point of US foreign policy and the commander in chief – even as a Nobel Peace laureate – will have to give an answer.
Vladimir Putin has made his choices to a barely covered aggression against Ukraine and ignoring any international law agreements not to do so and attempts to negotiate a peaceful solution.
So what is you answer Mr. President?