Let me tell you about the next war.

It will start sooner than you think — sometime between now and September. And it will be precipitated by the $700 million Russian deal this week to sell Tor air defense missile systems to Iran.

When the war begins, it will be between Iran and Israel. Before it ends, though, it may set the whole of the Middle East on fire, pulling in the United States, leaving a legacy of instability that will last for generations and permanently ending a century of American supremacy.

Despite the high stakes, the Bush administration seems barely to have noticed the danger posed by the Russian missile sale. But the signs are there, for those inclined to read them.

As international pressure over their nuclear program mounts, the Iranians have become increasingly bellicose toward the U.S. and Israel. On Monday, Iranian President Mahmoud Ahmadinejad said Israel was a "fake regime" that "cannot logically continue to live." On Wednesday, Ayatollah Ali Khamenei, Iran's supreme leader, warned that "if the U.S. ventured into any aggression on Iran, Iran will retaliate by damaging the U.S. interests worldwide."

Israel has upped the rhetorical heat as well. On Tuesday, Prime Minister Ehud Olmert reiterated Israel's determination to "make sure no one has the capability or the power to commit destruction against us."

This alone should make any observer jittery. In June 1981, Israel unilaterally launched an airstrike against a nuclear reactor near Baghdad. Iran's nuclear facilities are dispersed and well-concealed, making a pre-emptive Israeli strike far more difficult this time around. But there's no reason to doubt Israel's willingness to try.

Of course, there's no firm evidence that Iran has offensive nuclear capabilities. And even a successful military strike against Iran would be a risky move for Israel, potentially igniting regionwide instability. Absent external meddling, Israel has a substantial incentive to wait to see if a diplomatic solution can be found.

But Russian brinksmanship is about to remove Israel's incentive to pursue a peaceful diplomatic path.

Russian leaders continue to mouth the usual diplomatic platitudes about democracy and global cooperation, but Russia is actually playing a double game. On Tuesday, Russia launched a spy satellite for Israel, which the Israelis can use to monitor Iran's nuclear facilities. On the same day, Russian leaders confirmed their opposition to any U.N. Security Council effort to impose sanctions against Iran, and their intention to go through with the lucrative sale of 29 Tor M1 air defense missile systems to Iran.

"There are no circumstances which would get in the way of us carrying out our commitments in the field of military cooperation with Iran," declared Nikolai Spassky, deputy head of Russia's National Security Council.

The upcoming deployment of Tor missiles around Iranian nuclear sites dramatically changes the calculus in the Middle East, and it significantly increases the risk of a regional war. Once the missile systems are deployed, Iran's air defenses will become far more sophisticated, and Israel will likely lose whatever ability it now has to unilaterally destroy Iran's nuclear facilities.

The clock is ticking for Israel. To have a hope of succeeding, any unilateral Israeli strike against Iran must take place before September, when the Tor missile deployment is set to be completed.

At best, a conflict between Israel and Iran (with resulting civilian casualties) would further inflame anti-Israel sentiment in the Islamic world, with a consequent increase in terrorism, both against Israel and against the U.S., Israel's main foreign backer. At worst — if the U.S. gets drawn into the conflict directly — the entire Middle East could implode, terrorist attacks worldwide would increase, the already overstretched U.S. military would be badly damaged and U.S. global influence would wane — perhaps forever.

So what is Russia up to? Andrei Piontkovsky, a Russian political analyst, suggests that Russia's oil and gas oligarchs wouldn't shed any tears over a war in the Middle East, especially if it's a war that ensnares the U.S. and keeps oil prices high.

Even so, it may not be too late to avert a new war in the Middle East. A quiet but firm U.S. threat to boycott the G-8 summit in July in St. Petersburg might inspire Russian President Vladimir Putin to freeze the missile transfer. And a promise to facilitate Russian entry into the World Trade Organization might even get Russia's oil and gas oligarchs on board. Freezing the missile sale would buy crucial time to find a diplomatic solution to the stalemate over Iran's nuclear program.

Unfortunately, the Bush administration appears to be asleep at the wheel, too distracted by Iraq, skyrocketing gas prices and plummeting approval ratings to devote any attention to Russia's potentially catastrophic mischief.

Meanwhile, the clock is ticking.

Rosa Brooks is an associate professor at the University of Virginia School of Law. She wrote this commentary for the Los Angeles Times.