It is difficult to believe that President Barack Obama considers that the agreement between six countries and Iran on November 21, 2013 to limit temporarily some part of Iran's nuclear weapon and to allow Iran to continue enriching uranium up to 5% is a triumph for his view of diplomacy as the key factor for American foreign policy. He might be disillusioned by the events in Ukraine at the very same moment in November. They show that power politics and threats of imposing and increasing sanctions have proved to be more successful than discussions and negotiations with foreign leaders, desirable though these may be.

On November 21, 2013 Ukrainian President Viktor Yanukovych unexpectedly announced that he was postponing the signing of an association agreement, essentially a trade pact, with the European Union (EU) that was to take place at the EU summit meeting in the Lithuanian capital of Vilnius on November 29. After five years of negotiation he claimed he had been forced to postpone the signing by economic necessity and the need to protect those "most vulnerable."

In fact, Russian President Vladimir Putin had exerted political and economic pressure on the Ukrainian president to do so. The Obama Administration should understand not only the significance of this particular event regarding Ukraine, but also must now assess Russian eagerness to control or maintain power over former members of the Soviet Union.

Putin's suggestion that there be trilateral talks on the future of Ukraine evokes ominous echoes of the infamous pact between Hitler and Stalin in 1939 to divide up Poland. The Ukrainian Prime Minister, Mykola Azarov, acknowledged that Russia had "suggested" delaying signing the treaty and that instead negotiations should be conducted between Kiev, Moscow, and the EU. Putin had two years earlier already successfully pressured Yanukovych to shelve any plans to join NATO. He had threatened to target missiles against the country if it did so and if it accepted deployment of the U.S. missile defense shield.

For four years the EU has been trying to sign a free trade agreement with Ukraine, as well as one with other Eastern European countries. A compromise agreement would include EU concessions, reducing tariffs and facilitating travel without visas, while Ukraine in return would introduce democratic reforms. Equally important, the EU hoped this agreement would lead to limiting Russian control or influence over areas of Eastern Europe.

The EU had failed to achieve partnership with some of those countries in Eastern Europe. An arrangement with Belarus was halted after the election in 1994 of President Alexander Lukashenko who has since ruled in authoritarian fashion with insufficient respect for the rule of law. An association agreement with Armenia was to be signed in September 2013 but the country withdrew and decided to join the Russian Customs Union, a rival to the European Union. The EU looked for success with Ukraine which in fact had introduced a few reforms, though they were not fully implemented, in the legal system, in free trade, and by release of some political prisoners.

Another given reason for Yanukovych's decision to postpone the association agreement was his refusal to agree to one of the EU's conditions that he release Yulia Tymoshenko from prison. The United States also has called for her unconditional release. She was Yanukovych's political rival whom he narrowly defeated in the presidential election in 2010, when she won 45.47% of the vote. In a politically motivated trial she had been sentenced in 2011 to 7 years imprisonment for alleged abuse of authority and embezzlement in signing gas contracts with Russia in 2009 while in office as prime minister, the first female to hold the office in Ukraine.

Tymoshenko was not allowed to go abroad for medical treatment. She has threatened to start an indefinite hunger strike in solidarity with the protestors, more than 100,000, in Kiev who had demonstrated against the Ukrainian president for his decision not to sign the trade deal, and who were injured by the use of tear gas against them by the police.

More important and the real explanation of Yanukovych's decision was not diplomacy but Russian pressure and inducements. The EU was outbid by Russia which offered Ukraine more in terms of subsidies, lower gas prices, debt forgiveness, and duty free imports than the EU had in offering loans. Ukraine is dependent on Russia for 60% of its natural gas, and Russia has stopped supplies on a number of occasions. Russia has had the advantage in offering more specific, concrete benefits than the EU which called for a more democratic and constitutional Ukraine.

For months Moscow has exerted pressure on Ukraine and warned it would impose punitive measures if a trade deal were signed. It deliberately delayed examining Ukrainian trucks importing goods into Russia, and stopped some imports, such as steel and chocolates, thus decreasing the volume of Ukrainian exports. Calculations suggest that these actions cost Ukraine about $15 billion in lost trade. Russia warned that losses would be much greater and that it would increase taxes on Ukrainian exports if the country joined the EU. Ukrainian trade with the EU is greater than with Russia, though Moscow is still the largest individual trading partner. Ukraine is still the main outlet, through its pipeline transit network for export of Russian gas. It has suffered twice during the last seven years from cuts of oil supplies from Russia for political reasons.

The energetic Putin flexes muscle politically as well as physically. Ukraine was under Russian control from the 1700s until 1991 with the dissolution of the Soviet Union. Many Russians view Ukraine as culturally part of their nation and logically within its sphere of influence. Putin wants Ukraine to join the Customs Union led by Moscow, a Union that includes Belarus and Kazakhstan.

The significance of this episode of exercise of power by Moscow over Ukraine should not be lost on the White House. The American president need not take political lessons from the Russian president. Nevertheless, Obama's pledge to stretch out a hand diplomatically to America's enemies as well as to friends, though it may be an indication of politically correct moral righteousness and a self-congratulatory gesture, is not in itself the way to resolve the nuclear threat from Iran or the war in Syria. Nor is it likely to diminish the anti-Americanism of the belligerent Iranian regime. Avoiding war is essential, but so is the recognition of power, as exerted by Russia and increasingly by Islamic terrorism.

Michael Curtis is author of Jews, Antisemitism, and the Middle East.