Iran has notched up its level of confrontation in dealing with the outside world over the past weeks — not only with the West and the International Atomic Energy Agency, or IAEA, but also with neighboring oil-rich Arab monarchies. In the process, it has created problems for Russian diplomacy as well. The more deadlocked that negotiations become over Tehran’s nuclear program, the greater the likelihood that Israel will ultimately resort to a military strike against Iran’s nuclear facilities.

This possibility has put tremendous pressure on Iran’s ruling circle of mullahs. Their natural defensive response has been to make an emphatic appeal to Russia to deliver the S-300 surface-to-air missile system that it promised Iran in an agreement that the two countries signed in December 2005.

But Russia is in no hurry to deliver the S-300, pointing out that the contract does not specify a specific deadline for delivery. Following a hasty visit to the Foreign Ministry, the Iranian ambassador to Russia announced that Moscow would definitely deliver the sought-after missile system within two months, but the Kremlin remains silent.

All along, Moscow was betting that it could use the S-300 as a means of increasing its influence in the region. This was typical of the Kremlin’s active foreign policy in 2005, when the country was “getting up off its knees” amid sky-high oil prices. It was marked by a broad opposition to the United States to settle scores with Washington for its support of color revolutions in other former Soviet republics. Russia chose the Middle East as a fitting arena for that standoff — a region where it would renew special relationships with radical regimes first cultivated by Soviet leaders and later neglected under former President Boris Yeltsin. Recall that in April 2005 then-President Vladimir Putin visited Egypt, Israel and the Palestinian territories. He caused a scandal by informing the Israelis of his plan to renew military cooperation with Syria, including the delivery of an air defense missile system. Moreover, Russian offensive missiles ended up in the hands of Lebanese Hezbollah extremists, some of which rained down on Israelis in the war with Hezbollah in summer 2006.

The international political situation has changed ever since the administration of U.S. President Barack Obama “reset” relations with Moscow by canceling plans for deploying elements of its missile batteries in Central Europe. Russia’s response has been to step up its cooperation in the six-party talks,  consisting of the five permanent members of the United Nations Security Council and Germany, over the question of Iran. Judging by the Foreign Ministry’s latest statements that unequivocally condemn Tehran’s rejection of a compromise with the IAEA and the Group of Six nations, Moscow’s political position is now in line with most of the world community. This would explain why Tehran is so upset with Moscow.

In practical terms, however, Moscow is trying to establish an intermediary role between Iran and the West. That was one of the political goals of Energy Minister Sergei Shmatko’s when he visited Tehran recently. Shmatko signed several strategic cooperation projects between Moscow and Tehran, especially in the oil and gas sector. He also clearly went out of his way to avoid the prickly question of the undelivered S-300 system.

But Moscow has not remained completely silent on this issue. One high-ranking official attempted to explain to the Iranian side the reason for the delay in delivery. His rather peculiar reasoning was that by withholding the weapon system, Russia was forestalling Israel’s inevitable strike against facilities in Iran. This shows that Moscow understands the importance of the problem and that its actions can influence whether there will be peace or war in the Persian Gulf. It is anybody’s guess as to how Russia will extricate itself from the trap of its December 2005 agreement with Iran.

The real question is how Russia will preserve political solidarity with the Group of Six states while simultaneously retaining Tehran’s trust? In all likelihood, Moscow does not have a solution for this conundrum other than to rely on a lot of luck.

Alexander Shumilin is the director of Center for the Analysis of Middle East Conflicts with the Institute for U.S. and Canadian Studies at the Russian Academy of Sciences.