Russian President Vladimir Putin is the most dangerous dictator Europe has seen since the death of Stalin in 1953.  The United States and our NATO allies must not shrink from the challenge he presents.  Dangerous events in the Middle East must not distract us.

Putin has consolidated his power in Moscow.  He is a dictator answerable at this time to no one.  He controls the media, the business oligarchs who dominate the economy of Russia, the military and the parliament.  It appears there is no institutional process available to remove Putin from power.  Putin can do what he wants with his country and his military.  He has shown he will ruthlessly repress opposition wherever it arises.  Add to this a deep anger and contempt for the West coupled with a messianic vision of a restored Slavic, Russian Orthodox Empire dominated from Moscow and we have a danger in Europe that must be confronted.

Now is the time for the United States and our NATO allies to publicly support military assistance to Ukraine including modern anti-tank weapons and the equipment needed to resist the Russian invasion during the upcoming winter months.  We should not be timid about helping people in Europe who are ready to fight for their freedom.  But we should not mislead the people of Ukraine like the U.S. did with Hungary in 1956.  Ukrainians should know they will have to win their freedom and Russia will know it will pay a terrible price if it chooses to try to militarily dominate Ukraine.

The West must decide whether it is going to continue to help finance Putin’s aggression.   Private investment from the West coupled with the purchase of billions of dollars of oil and gas help finance Putin’s army.  It is hard for business and political leaders to accept how badly they have misread Putin.  The U.S and the E.U. must impose the toughest economic sanctions possible on Russia and the sooner the better.  The gradual approach has not worked.  The next target should be the Russian banking system.  Russian banks should be denied access to Western capital markets.  Russia should know that if it persists with its aggression it will be kicked out of the WTO.  

Steps must be taken to reduce the global price of oil.  Sanctions against the energy sector must be coupled with steps to bring new sources of energy into the European market.  All sources must be considered immediately.  If the price of oil could be reduced to about $80 a barrel, the Russian government would be in a financial free fall.

The U.S. and the E.U. must also be willing to provide humanitarian assistance to the people of Ukraine during the coming months as they deal with the prospect of Russia cutting off the flow of natural gas.  

The message to President Putin is simple: If Russia wants to be an economic partner with the West and enjoy access to critically needed capital, consumer goods and the good life of neighboring countries in Europe, it must follow some basic rules.  Rule number one is that you do not invade a neighboring country.  If Putin choses to violate the basic norms of international law and lie about it to the world he is making a choice for his country that will have terrible economic consequences.

The U.S. and Europe must make clear that we desire a peaceful and mutually beneficial relationship with Russia and we are prepared to accept an independent Ukraine that is a true bridge between East and West.  Neither E.U. membership nor NATO membership is required to achieve this unique position for Ukraine as long as Russia accepts an independent Ukraine that can truly seek its own future free from military invasion and “little green men’ like the world has seen in Crimea and Eastern Ukraine.

In spite of the European dependence on Russia for energy, especially natural gas, Russia needs Western Europe a lot more than Western Europe needs Russia.  Putin knows this.   He is betting that the people in Europe and the U.S. are soft and are not tough enough to make the short term sacrifices necessary to confront him.

There was another man with a grandiose vision in the 1930s who made the same calculus. We must not forget that ignoring aggression or appeasing it only encourages more aggression from egotistical people like Putin.

President Obama and the congress need to make sure that President Poroshenko goes back to Kiev with more than a few warm ovations from the joint session of congress.

Jim Slattery is head of Wiley Rein LLP’s public policy group and former six-term U.S. congressman (D-Kan.).  Mr. Slattery was instrumental in the former Ukrainian Prime Minister Yulia Tymoshenko’s release from prison earlier this year, and has been present as an election monitor in the country’s past three elections.