After months vowing to get US troops home from Iraq, Barack Obama has succumbed in the war's political entanglements, struggling to explain his plan in the light of recent security gains.

More than five years after the US invasion, the Iraq war is now enmeshing not only the Bush administration which started it. but both men fitting to inherit it, Democratic White House hopeful Obamaand Republican John McCain.

Obama is torn between a vow to end the war, which underpinned his win over Democratic foe Hillary Clinton and Republican claims his plan invites US humiliation, would

delight terrorists and waste gains bought in American blood.

The war remains broadly unpopular, but it has fallen behind the economy as the top campaign issue, following a lull in violence. Last month, more American troops were killed in Afghanistan than Iraq.

Under rising Republican pressure, Obama on Thursday said he may "refine" his policies after meeting US commanders in Iraq on a trip expected this month.

But hours later, he hurriedly called a second press conference to insist he had not made the "flip flop" on Iraq that many observers are expecting, as he retools his message for the political centre ground.