One of the principles of politics and world power equations is that they are never static,  but dynamic and change at no stated interval. Thus we saw the signing of the 1938 Munich Pact when Nevile Chamberlain the British premier announced that " we have won peace for our time". Chamberlain woefully underestimated Hitler and the result was that Hitler annexed Austria and the Sudetenland and just 2 years later WWII broke out.

Another example we have is the famous non-aggression pact between Hitler and Stalin of 1939. The Soviet foreign minister Molotov went to Germany for the signing of the pact amid much fanfare. Yet on 22 June 1941, the German Wehrmacht launched an invasion of Russia. Thus nothing is static in the world of realpolitik.

Iran is an important power in Central Asia. For decades Iran was part of the American sphere of influence. The Shah of Iran was an American stooge and he was a strong partner in the various defense pacts like CENTO, Baghdad Pact against Russia. The Shah was also a tyrant and he executed hardline Muslim like animals. His favorite punishment ( authorized by him) was to carry the opponents to his regime in a helicopter and after tieing the man's  hands and legs drop him from a height of nearly 8-10000 ft.

The Shah was overthrown by a popular revolution and the Iranians threw out the Americans. They began to refer to America as the "great Satan". The Shah was forsaken and a one-time ally of America was not even allowed to spend any time there as the US government sent him away. Only Egypt under Anwar Sadat gave refuge to the Shah. The world of realpolitik changed dramatically.

The Americans for long have been trying to regain influence in Iran. President Obama thought that by agreeing to Iranian demands and unfreezing their assets on the nuclear issue in return for some flimsy assurances, Iran will come back to the American fold.

Unfortunately, a battle opened up in the Middle East and Iraq in particular after the folly of George Bush in removing Saddam. Now Saddam was a Sunni and the majority of the Iraqi population is Shia. This was fertile ground for a conflict and the ISIS which is basically a Suni outfit was born. It began to execute Shias and Iran obviously came on the side of the Shia.

In Syria, the Iranians backed Assad who was also a Russian ally and as both Russia and Iran were on the same footing  their interests converged. The Americans were keen to remove Assad, simply because he never towed the American line. The Iranians were thus once again crossing swords with the West and America. Obama's policy of appeasement with Iran collapsed like a sand castle. 

Putin is a shrewd manipulator and his overtures to Iran cut a lot of ice with the Iran leadership. As both faced America, it was natural for Iran to align with Russia. The result is the beginning of a military collaboration which is anti-America and its ally in the Middle East.

The relationship has now been strengthened with the Russians using the TU-22M supersonic bomber and operating it from the Iranian airbase to bomb the opponents of Saddam. This help from Iran is perhaps the beginning of a military relationship with Russia. The Russian bombers had earlier to fly from a distance of 1900 km to bomb Syria, but now they take off from a base close to Tehran and the distance is reduced to just 630 km. The TU -22 with a speed of 2350 km  per hour is a Mach II bomber and there is no similar plane in the world, none even with the USA and China.

The plane needs a longish airfield to operate and the Iranian have such an airfield. The bombers have been flying over Iraq to hit targets of the opponents of Syria. The TU-22 also called the Backfire is a lethal plane and the Americans are worried, more at the possible military alliance of Iran with America. Iran has never forgiven America for the atrocities of the Shah and also for supporting Israel. 

The Russian bombers flew over Iraq after informing the USAF as per a pact between Russia and America signed a few years back. The world of realpolitik is changing and a country that was once part of the US alliance against Russia is now allowing the Russian Air Force to operate from its airfield. It's perhaps the budding of a military alliance and America will be perturbed.