Nature abhors a vacuum.
If you look through periods of history over the last two thousand years or so, every so often you see periods of time when the predominant power in a region loses its influence. This may be through internal dissent or strife, economic overstretch, or a lack of will to govern.
Historians often call these blips in history "periods of transition", between one state of affairs and another. This is when the "dialectic" of the time is in dispute, before another narrative appears that fuses together the old and the new.
A short history of nearly everything
Pretensions aside, history is full of these examples. Alexander The Great conquered the Middle East and beyond due as much to the relative weakness of other powers at the time as his own organisation. His Greek-speaking empire fragmented after his death, whose division of power bases lead in time to the rise of Rome.
Rome then became a victim of its own success, when it was financially overwhelmed by the inefficiency of its state and the many tribes that occupied the empire from the Eurasian steppe; what we call today "imperial over-stretch".
The result of this was the so-called "Dark Ages", when the remainder of the Roman Empire in the East morphed in the thousand-year Byzantine Empire, while the Western half of Europe became a patchwork of weak and fluid national entities until the largest and most stable part became, in time, the Holy Roman Empire.
The weakness and fluidity of the "Dark Ages" was one factor for the rise of Islam, which was fortunate to have a good sense of timing. Islam conquered the Middle East, North Africa and the Iberian peninsula due to the relative weakness of the other main powers at that time: in the Middle East and North Africa, the Byzantines were weakened from fighting a long war with Persia. The Muslim Arabs took full advantage. Pushing west, the Arabs crossed into Iberia and pushed north, over the Pyrenees until they were pushed back in the middle of France, and left to consolidate their position in modern-day Spin for the next five hundred years.
Skipping forward, the spread of the Mongol Empire (more about them here) was also due to key factors such as the relative weakness of their rivals at the time. The Mongols quickly overwhelmed the embryonic Russian state, and got as far as Eastern and Central Europe, devastating half of the continent and wiping out the armies put before it. Only the untimely (but for Europe, fortunate) death of the Mongol khan put a halt to the advance. With the death of the khan, the Mongols became pre-occupied with the battle for succession, and Europe was never again a serious priority for them. Instead, Asia and the Middle East bore the brunt of their attention.
In time, the Mongols also lost their pre-eminence. The story of the next five hundred years, from the end of Mongol rule in China towards the end of the 14th century (which coincided with the renaissance in Europe) to the end of the 19th century (which coincided with the rise of the modern democratic state), we see a common pattern. We see the rise and fall of imperial powers like waves in the sea. And we see the rise of new powers happening on the back of the weakness of others.
Stepping into the breach
When the influence of an imperial power (or state actor, to use a modern term) recedes like a wave, it leaves an empty space; a stretch of virgin beach, if you like, ready to be inhabited by a new set of occupiers. In 2014, the two events of the year so far have been the Ukraine Crisis and, more recently, the sudden rise to power of ISIS in the Middle East, an al-Qaeda-inspired extremist force.
The factors that led to the Ukraine Crisis include, as always, the relative weakness of the imperial actor, which is exploited by another (opportunistic) power. In the case of Ukraine, the "imperial actor" was jointly the USA and the EU; on an economic level the EU was driving for Ukraine to enter under its wing, while on a political and diplomatic level, the USA saw a chance to bring Ukraine closer to its orbit.
The problem here was the weakness of both the EU and the USA's position. They had misread (and underestimated) Russia's position (and therefore response). Due to the weakness of both the EU and the USA, they failed to back up their rhetoric with firm actions; relying on the power of threats alone, their actions turned out to be predictably toothless. Ukraine now has a weak central government supported by a toothless West.
It is the weakness of the EU and the USA that is responsible for Russia's response. Putin correctly calculated that the the West lacked the collective will to follow up its words with actions. The West is now at least partly to blame for encouraging the Ukrainian opposition into a position that requires a forceful Russian response.
Now Ukraine is divided in almost the same manner as the USA was back its Civil War, with a separatist region fighting against a government of the north. In this narrative, Kiev is the new Washington, with Donetsk acting as the "southern capital". By a ironic twist of fate, the southern separatists even have a flag that closely resembles that of the old Confederacy, and call their unified "state" the "Confederation of New Russia". This "CNR" is bankrolled and militarily supported by Russia, in the same way that France supported the Americans during the War of Independence. The old Confederacy never got the real support from Britain or others that would have given it a fighting chance during the civil war; the modern-day CNR, however, stands a much better chance of frustrating and wearing-down Kiev through sheer attrition and a mounting cost in blood and treasure, with the support of Russia. Kiev cannot afford a war in the long-term. Russia can.
In the war-zone of east Ukraine, it is the drip-drip of military casualties that may wear down Kiev over time. Moscow's support for the separatists is covert, but consistent. Moscow looks unlikely to back down from its covert military support as long as the West is weak. In the psychology of the Kremlin, if Ukraine is weak, then the West is weak. This gives Moscow all the reason to continue doing what it is doing; the weakness of Kiev demonstrates the strength of Moscow, with Russia stepping into the breach left behind by the West's geo-political weakness.
The army of Islam
The Arab Spring has had many consequences. The most worrying (yet predictable) is the increased power that Islamic extremism has across the the Middle East. The dictatorial states of the Middle East are generally awful, but brought (imposed) stability to the region, to the benefit of the West. In many cases, most of all Syria and Iraq, that stability is effectively destroyed.
The Syrian Civil War is now more than three years old. Few people predicted it would last this long, including this writer. There is now a kind of "unstable stability" with Syria, with the government controlling roughly the south, centre and the west, the pro-Western Sunni rebels controlling the north, and the Sunni Muslim extremists controlling the east. The war is now bogged-down into a stalemate of attrition, with neither side looking close to making any significant advances for the foreseeable future.
Except for the extremists. ISIS, an al-Qaeda-inspired militia, has now evolved from being a "mere" terror group into something like an army. The breakneck speed with which they took control of Mosul, Iraq's biggest city in the north, and a swathe of Sunni-inhabited territory across northern and western Iraq, seemed to come out of the blue. As a result of this, ISIS now control a "de facto" state encompassing eastern Syria, and northern and western Iraq, straddling both sides of the Euphrates valley for hundreds of miles.
One of the most stunning successes was looting Mosul's banks after they took the city; in what must surely be the biggest collective bank robbery in history, ISIS wiped Mosul's banks clean of half a billion dollars in gold and money.
This event compares historically with how the Bolsheviks financed their agenda with bank robberies and other means in the years before they came to power; the most famous was the 1907 Tbilisi robbery in broad daylight in what is now Freedom Square, orchestrated by Stalin (more on his early years here). That robbery was the largest ever at that time.
Their success in Iraq is due to the weakness of support for the government in Sunni-inhabited areas of Iraq. The USA military left Iraq more than two years ago, to be defended by an army comprised of Shias, for the government comprised of Shias. While Kurds more-or-less run their own affairs in their own territory in the north, the Sunni are left powerless, and at the whim of the Shia-led government. ISIS has now stepped into this breach, with evidence that former Baathist officers had done some kind of deal with ISIS, and may also account for the swelling of ISIS's ranks in Iraq. This would also explain why there was no resistance to ISIS taking control of many Sunni-inhabited cities. In other words, the Sunnis of Iraq now have an army of their own to match the "government" Shia army, and the Kurdish peshmergas.
The ingredients are all there for a full-blown civil war like in Syria.
Where does this leave American foreign policy?
Obama's strategy after the reign of George W Bush had been to repair diplomacy and restore America's reputation as a "peacemaker" rather than a warmonger.
Ignoring the ratcheting-up of the "drone wars" under Obama's watch, it's hard for other "state actors" to ignore the impression that America has now become more consumed by internal politics and introspection (given the rise of The Tea Party - see here and here), and that Obama sees the USA's relative decline as inevitable given the rise of China.
Putting this into consideration, the result is a moral "free-for-all". The UN has become an open joke among the more belligerent powers of the world, to be used as a theatre more than a diplomatic space. With the relative isolationism of the USA under Obama's watch (and likely to continue under his successor, regardless of which party they are from), the world resembles those periods of transition in history gone by, where other powers race to fill in the space left behind by the receding imperial power.
On the evidence so far, Russia, China and Islamic extremists seem to be the beneficiaries of this.