The bottom line remains this. Barack Obama is sending 30,000 more US troops to Afghanistan.

That is the most important element of his speech at West Point this week. The politics, of course, are fascinating.

Obama shares one political characteristic with Kevin Rudd: a pervasive postmodern desire to win both sides of every argument.

Thus, for those who oppose the US commitment in Afghanistan there is the prospect of a US withdrawal beginning in July 2011.

But to those who support the war in Afghanistan, and believe for any of a variety of reasons that it's winnable and worth winning, there is the obvious and inescapable central fact that Obama is sending 30,000 more troops to get the job done.

When this surge is complete, Obama will have tripled the number of US troops in Afghanistan. That is not the action of a peacenik, a lefty or a Jimmy Carter.

Then, when you look at the speech a bit more closely you find that the withdrawal is not a date when US troops will all leave.

Senior US officials on background, transcripts of which were circulated to journalists, explained the withdrawal would be based on the conditions prevailing at the time, and might be slow.

In other words, quite rightly, Obama has surged and escalated, and left his later options open.

Part of the speech read like George W. Bush. Obama said, for example: "The struggle against violent extremism will not be finished quickly and it extends well beyond Afghanistan and Pakistan. It will be an enduring test of our free society, and our leadership in the world." Substitute terrorism for violent extremism and it's pure Bush.

As Obama is demonstrating, a thing can be true even if George W. Bush said it was true. In one of the background briefings, a US official was asked to react to Iranian charges that US policy was the same under Obama as under Bush. I'm not surprised there is continuity (or words to that effect), the official said, the US is pursuing its national interests. And, he might have added, its values.

This speech had passages in which Obama was much stronger than ever before in defending American exceptionalism, again in a long tradition of US presidents. Obama said: "We must make it clear to every man, woman and child around the world who lives under the dark cloud of tyranny that America will speak out on behalf of their human rights, and tend to the light of freedom, and justice, and opportunity, and respect for the dignity of all peoples."

Obama also made it abundantly clear that he doesn't think he's the first president to embrace these ideals. Instead, here is how he described America's record: "Since the days of Franklin Roosevelt, and the service and sacrifice of our grandparents, our country has borne a special burden in global affairs. We have spilled American blood in many countries on multiple continents. We have spent our revenue to help others rebuild from rubble and develop their own economies . . . We have not always been thanked for these efforts, and we have at times made mistakes. But more than any other nation, the United States of America has underwritten global security for over six decades -- a time that, for all its problems, has seen walls come down, markets open, billions lifted from poverty, unparalleled scientific progress, and advancing frontiers of human liberty. For unlike the great powers of old, we have not sought world domination."

I found these words profoundly reassuring and much more important than any of Obama's more obviously successful and stylish speeches. For these words, and the decision to send the troops to Afghanistan, demonstrate that Obama is fully a national security president, that he understands fully America's unique security role and is wholly proud of the US record (while of course acknowledging mistakes).

Naturally, there are some problems with the decision. The commander on the ground, General Stanley McChrystal, asked for 40,000 troops, and he probably knows better than anyone what he needs. The policy review took too long, three months.

Obama points out that the troops couldn't have left any earlier, presumably because of seasonal conditions in Afghanistan. But the length of the review unintentionally sent a message of weakness of resolve.

The international community ought to cut Obama some slack here. This is a pretty brave decision. Obama is doing what all the pundits (myself included) have said he never does -- he's defying his base, he's taking a tough decision, he's taking a probably unpopular decision, he's risking the lives of thousands of young Americans and he's probably risking his presidency. I don't know about you, but for me that pretty much establishes the authenticity, the substance and the grit in this decision. As is almost always the case, it is overwhelmingly in the interests of global peace and security for him to succeed.

Obama hopes he'll get some more troops from his NATO allies. He was too polite to ask Kevin Rudd for more troops when Rudd visited Washington a few days ago. Rudd did do a good thing in increasing Australia's police training effort and our civilian aid, but if ever there was a time when we should increase our troop commitment it's now, as part of Obama's surge. Obama deserves it. Afghanistan needs it. And if ever there's a time when we could usefully add another 1000 soldiers to the 1500 we have there already, it's now, as part of a US and NATO surge. Even the British, with 10,000 troops in Afghanistan already, are adding 500. If our defence force cannot sustain another 1000 troops in Afghanistan, on top of the 1500 already there, we are not getting anything remotely like value for money from our $22 billion defence budget.

Obama wants his new troops to train the Afghan security forces, but to do this properly takes time. Part of the disaster in the early years in Iraq came from notionally training huge numbers of Iraqis but not paying attention to the quality of the training.

Quality training comes from mentoring and partnering local troops. That means combat troops fighting alongside their Afghan allies. Effective training in a context like Afghanistan cannot take place solely in barracks.

Straight after Obama's speech I spoke by phone to US Assistant Secretary of State for East Asia and the Pacific Kurt Campbell, who had several messages. One was to thank "Asian friends and allies for the big effort they're making out of area".

By this Campbell meant Asian nations, including Australia, contributing to the US-led effort in Afghanistan, some through military deployments, others through aid. Japan, for example, virtually paid all the Afghan police salaries and has committed more than $US5 billion ($5.4bn) extra aid.

Secondly, he wanted to assure Asian friends and allies that the US, after a rigorous policy review, was fully committed to reversing the Taliban's momentum, increasing the capacity of Afghan institutions, training Afghan forces so they could perform, and increasing the civilian aid flowing to Afghanistan. I imagine US diplomats all over the world are reinforcing this message: the Obama administration is fully committed to its strategy.

Campbell wanted to thank Australia for its efforts in Afghanistan. He acknowledged the increase in our troop numbers earlier this year, and said: "Australia has been generous and extremely effective in the kinds of capabilities they've deployed."

He made a point, too, about Obama mentioning a date for beginning a US troop withdrawal. "That was aimed as much at key Afghan institutions as at domestic (US) public opinion. It's critical that Afghan institutions step up. If they don't step up then it's impossible for the US to step up."

Campbell's point echoes Obama's -- the Americans cannot win this war without an effective Afghan partner, to wit, Hamid Karzai's government.

Campbell also underscored the extremely serious nature of what was at stake. Obama rightly drew attention to the terrorism, directed at the US and other nations, including Australia, that has originated either in Afghanistan or Pakistan. He said al-Qa'ida, which was sheltered and enabled by the Taliban in Afghanistan, was seeking nuclear weapons and would not hesitate to use them. (Another thing Bush said that turned out to be true.)

With unemployment at 10 per cent, in the midst of financial difficulties, in the face of strident opposition from his base and sagging popularity numbers, Obama is committing 30,000 extra troops and US $30 billion in extra money for the next year in Afghanistan.

It is overwhelmingly in Australia's interests, overwhelmingly in the world's interests, that the US succeed in this effort.