For the U.S. military, it's the million dollar question -- or rather the $687 billion question, according to a recent estimate of the Iraq war's total cost. Is Iraq now stable enough for them to take a permanent back seat?

The short answer is no one knows. The only way they were ever going to find out was to leave Iraq's own forces to it and hope the whole thing doesn't come tumbling down. They started doing that on Tuesday when they pulled out of Iraqi cities.

It's been an encouraging start. A big bomb in Kirkuk cast a shadow over Iraq's celebrations of its new-found sovereignty, but since then things have been relatively quiet. Militants might try to take advantage by stepping up attacks, but for the moment they seem content with celebrating a "victory" over the occupation -- and setting off the odd bomb, of course.

The United States' coalition partners have for the most part long since departed. British forces handed over southern Iraq to the Americans in April, but since 2007 their 4,000 odd troops left had been largely confined to Basra airport anyway.

And one thing the crystal ball gazers have learned about Iraq's hugely complicated, many-sided conflict is that the past is rarely a reliable guide to the future.

When optimists thought Iraq was poised to enjoy democracy after the fall of Saddam, it spiralled into years of bloody insurgency and sectarian killing. Later, just when it seemed all hope was lost and Iraq would have to be partitioned, things starting getting dramatically better.

The idea that Iraqi forces aren't ready to take on the country's security usually centre on claims that they are untested, not well trained or infiltrated with militiamen.

But few deny they look more professional and integrated now than anyone would have thought possible two years ago. They might still be full of militiamen, but those militiamen are no longer kidnapping or killing political rivals, as in the past.

And there are clearly some things the Iraqis do better. For one thing, they know the language and understand the culture.

When I was on a U.S. patrol in Iraq's troubled Diyala province, a U.S. unit nearby accidentallly shot and wounded a civilian in Jalawla town, forcing them to vacate it because a public outcry would put other soldiers at risk of attack.

What they had done is fire a warning shot at a vehicle after the driver failed to heed a command -- in English -- to stay back. But few Iraqis in rural areas speak basic English.

The real test will be when U.S. pulls all combat forces out, under President Barack Obama's orders, by September next year.

Many Iraqis I've spoken too seem convinced the insurgents are just biding their time, sharpening their knives and stockpiling explosives waiting to reignite the conflict.

But whether or not Iraq can look after itself, at some point the Americans have to say: Look, we've done our best to get the lid back on Pandora's Box. Now it's over to you.

The United States is aiming to send 20,000 to 30,000 extra troops to Afghanistan by the beginning of next summer, according to the chairman of the U.S. Joint Chiefs of Staff.  The plan is not unexpected, and from a military point of view is meant to allow U.S. and NATO troops not just to clear out Taliban insurgents but also to bring enough stability to allow economic development, as highlighted in this analysis by Reuters Kabul correspondent Jon Hemming.

But does it still make sense after the Mumbai attacks -- intentionally or otherwise -- sabotaged the peace process between India and Pakistan?

As discussed many times on this blog, most recently here, a crucial element of President-elect Barack Obama's Afghan strategy was to combine sending extra troops with a new diplomatic approach looking at the Afghanistan-Pakistan-India region as a whole. The argument was that Pakistan would never fully turn its back on Islamist militants as long as it felt threatened by India on its eastern border and by growing Indian influence in Afghanistan on its western border.  India and Pakistan, so the argument went, should therefore be encouraged to make peace over Kashmir, to reduce tensions in Afghanistan and pave the way for a successful operation by the extra U.S. troops.

Where does that plan stand now? India-Pakistan relations are extremely strained and vulnerable to any second militant attack on India. It's hard to imagine the two countries sitting down any time soon for serious peace talks, and certainly not at the United States' behest, given that outside interference on Kashmir has always been anathema to India.

Yet as the Soviet Union discovered during its failed occupation of Afghanistan from 1979 to 1989, no matter how many troops you send in, you can't win there as long as the Islamist mujahideen have sanctuary in Pakistan.  The United States knows this too having backed the mujahideen against the Soviets (this being a war that America has fought on both sides), which is presumably why it had begun to look at Afghanistan in a broader regional context.

So have the Americans reverted to a piecemeal approach with this plan to send in the extra troops? Are they just pushing on regardless and hoping for the best, perhaps thinking they have no other choice? Or should they have gone back to the drawing-board post-Mumbai and come up with a different plan?