The memorandum appeared on 10 July in the Sunday edition of the British tabloid "Daily Mail" -- and British officials have confirmed that the leaked document is genuine.
As drawn up by British Defense Secretary John Reid, the memorandum foresees as one option the withdrawal of more than 100,000 allied troops by next year. Most of these would be U.S. forces, but British troops in southern Iraq would be scaled down by some 60 percent to only 3,000 soldiers.
The memo, as quoted, refers to "emerging U.S. plans" that it says assume that 14 out of the 18 Iraqi provinces could be handed over to Iraqi control by early 2006. This would allow a deep cut in the troop numbers of the U.S.-led coalition from 176,000 to 66,000.
The timing of the disclosure of the memo -- in the same week that more than 50 people were killed and 700 injured in four bomb explosions in London -- is unusual, says security expert Jonathan Lindley of the Royal United Services Institute in London.
"The existence of the memo is not at all surprising, these sorts of plans exist within the nature of military planning; the more interesting question is why it was leaked at this time; which is possibly indicative of dissent within the ministry of defense," Lindley said.
Could this therefore indicate growing discontent in government ranks with Prime Minister Tony Blair's policy of firm commitment to pursuing the insurgency in Iraq until it is defeated? After all, Britain will soon take over a lead role in the NATO-led troop force in Afghanistan, which will put the British military under strain to meet its present level of commitment in Iraq.
Analyst Toby Dodge of the International Institute of Strategic Studies in London, believes that at least at top level, meaning Blair and U.S. President George Bush, there is absolutely no weakening of the commitment to Iraq.
"You've got massive conviction [at that top level] that they are going to stay the course [though] they are not quite sure what staying the course means," Dodge said. "But at a lower level, say in the [British] ministry of defense, you have a juggling of troops and commitments, trying to work out how it goes."
The leaked memo also refers to differences within the U.S. military on exactly how to proceed, saying that military leaders at the Pentagon and at the U.S. regional Central Command, favor a quicker troop drawdown than do the senior officers on the ground in Iraq.
Another question raised by the secret memo is whether a withdrawal of coalition troops from certain regions of Iraq and not from others would interfere with nation-building in the post-Saddam Hussein era.
In other words, would a long-term troop concentration in the areas of the Sunni insurgency allow the Kurdish north and the Shi'ite south to go their own way, possibly leading to dismemberment of the country?
"Because there is no state in Iraq, because the government has been very bad at building the state, as have the Americans and British as well, a high level of 'localism' is present, so that if you then look at the regions, you have a movement in Basrah [in the south] for radical autonomy, you have the [similarly minded] Kurds in the north," Dodge said. "We are not at [a decisive point] yet, but the longer that state-building fails, the more pressure there is going to be for exactly that, [a break up of the country]."
Dodge said, however, that he believes an assumption that most of Iraq's provinces could be returned to the control of Iraqi security forces alone by next year is just "wishful thinking."
He said that, so far, only a very few small areas have been placed under the full control of the Iraqis, and U.S. commanders on the ground consider that the Iraqi forces do not have the command and control structures to handle much more.
He noted that all previous hopes of being able to withdraw large numbers of coalition troops have shattered against the reality that the insurgents remain strong, and that the Iraqi Army is not able to deal with them on its own.