Possibly overcome with hubris from throwing his weight around in Pacific island-nations, John Howard has taken the extraordinary step of thinking he can interfere in U.S. domestic politics. Not that I would decry an Australian politician speaking out about U.S. politics per se, but it's actually a very different position to that that Howard's historically held, namely that Australia is ancillary to the U.S.'s decision to be in Iraq, not a campaigner for the U.S. to be in Iraq. This puts Howard on an extreme right fringe of global politics that even neo-conservatives are deserting in droves.
Barak Obama's retort to Howard is brilliant: he points out that Australia is not itself proportionally committing to the war in Iraq, so it hardly behoves Howard to tell American politicians to continue doing something that he will not.
The revolting Alexander Downer hit back, saying that Australia's small size should be taken into account, and that committing twenty thousand Australian troops would mean committing half of Australia's army. Well, this second claim is entirely true, but not in itself a reason not to commit to Iraq. The reason Australia can't commit half it's armed forces to Iraq is because it's already using them to occupy other countries. Moreover, Obama actually called for Australia to call up 20,000 troops, not simply deploy its currently-serving ones – as should be well-known, many in the US forces are reservists.
The claim that Australia size explains its inability to field 20,000 troops is ridiculous. Obama's demand is fairly proportional to Australia's size – since the US population is 15 times as large as Australia, Obama is effectively calling on Australia to deploy twice as many troops per capita as the US, but he could just as well have said 10,000 – Australia's current contribution to the occupation is many times smaller than this.
(sorry there are no reference links. By the time I wrote this, the news coverage was dominated by the intra-Australian dimension to the controversy.)