Obama's secret trip to Afghanistan

Presidents Obama and Karzai signed the Strategic Partnership Agreement after 19 months of talks

Air Force One touched down in Afghanistan in the dead of night.

The lights didn't come on when President Barack Obama emerged, and he was illuminated only briefly by the flash of cameras.

Great secrecy has surrounded the visit, but the president will hope there is huge publicity about what he's doing.

Before he formally launches his re-election campaign, he wants to stress that the war is over, but he is not leaving Afghanistan in the lurch.

He went to the palace to sign a Strategic Partnership Agreement, which has been 19 difficult months in the making.

It makes clear the US does not seek permanent military bases in Afghanistan but will "provide a long term framework for security and defence co-operation".

The president has already spoken to the troops, telling them that they embodied the best of American values and they would not be forgotten when they were back home and out of uniform.

He will make a major address to the American people tonight, saying that Afghan troops will be in the lead in combat roles from next year onwards, but there will be no new announcement about troop withdrawal.