The public statement by Iraqi chief of staff Lt. General Babakr Zebari, at a defense conference that the Iraqi army would not be ready to stand on its own until 2020 and US troops should remain until then is not a statement about security issues in general but is a highly ethno-sectarian piece of insubordination.
Unsurprisingly, the elected prime minister of Iraq and head of the current caretaker government, Nuri al-Maliki, promptly refuted Zebari and insisted on civilian control of this decision-making. As prime minister, al-Maliki is beholden to the elected parliament, which set the timetable for withdrawal. The Obama White House is also committed to the withdrawal.
Zebari is an old-time Kurdish guerrilla and a prominent member of Masoud Barzani's Kurdistan Democratic Party. (That the Guardian article above did not mention this background is incomprehensible to me; I really like journalists and especially ones who risk all by going out to places like Baghdad, and don't want to be needlessly critical, but when reporting neglects essential context it does a disservice to readers.)
The Kurds have many reasons for wanting the US military to stay in Iraq. They have established what is for all intents and purposes an independent state in what had been 3 provinces of Iraq (though by now the provincial boundaries and administrative apparatuses have long since been erased), called Kurdistan. Kurdistan is the Taiwan of the Middle East, a separate and independent nation that cannot be so named without causing a war (or a whole set of wars). But Kurdistan gives out visas and refuses to allow Iraqi army troops on its soil and does foreign contracts without consulting Baghdad, so what would you call it?
Despite being semi-autonomous, the Kurds also have a strange relationship to the Baghdad government, electing members of its parliament and at present holding the presidency of the country. Some compare this situation to Quebec in Canada, but that province has far, far fewer perquisites than does Kurdistan. It is more as though Jefferson Davis served in Abraham Lincoln's cabinet and Robert E. Lee was a high ranking staff officer in the Union army as well as in the Confederate.
Kurdish nationalism in Iraq is not satisfied with this relatively advantageous situation (de facto separatism plus powerful influence on the central government). Kurdistan nationalists want to annex part or all of several other Iraqi provinces that have substantial Kurdish populations. The Arab population of Iraq (both Sunnis and Shiites) is die-hard opposed to any expansion of Kurdistan at the expense of the territory of Arab Iraq, though virtually everyone is willing to let the Kurds retain their current territory and special privileges.
There have been clashes between the Kurdistan military, the Peshmerga, and the regular Iraqi army, in parts of Iraq as far as 200 miles from the Kurdistan border, because the Peshmerga has taken control there. The situation threatens another civil war in Iraq, and outgoing US commander Gen. Ray Odierno responded by having US troops patrol with both Peshmerga and regular Iraqi army units so as to avoid firefights between the two. Since the US will less and less be in a position to provide this mediation service, Odierno suggested that United Nations troops be brought in to fulfill it, but met a firestorm of protest from Iraqis eager to be out from under the long years of deadly UN caretaker status (Iraq is one of the UN's great failures, where it is responsible for killing large numbers of civilians with its regime sanctions, and of destroying a promising developing economy, and of failing to prevent an illegal and aggressive war on the country by GW Bush).
The US military has consistently sided with the Kurds in both military and political affairs, so it is unsurprising that Zebari fears their departure. Without a US protectorate, the Kurds will face Arab Iraq alone. Moreover, Arab politicians in Baghdad who want to block Kurdistan expansionism have on several occasions already sought support from Turkey in this endeavor, and such a Baghdad-Ankara alliance against the annexation of Kirkuk and of parts of Ninevah and Diyala Provinces is likely to strengthen and be cemented when the US departs.
My own view is that the KDP's romantic territorial nationalism is anachronistic and inappropriate to a Gulf oil state, and likely to be undermined by economic developments. There is much more petroleum in the Shiite south than in Kurdistan, and pumping and refining it will require a big skilled labor force. Large numbers of Kurds will almost certainly be drawn down to Basra Province to work the Rumaila and other fields (and there is more black gold in Maysan and elsewhere not yet exploited). Just as Kurdish nationalism in Turkey was blunted by the way the Kurds were spread around the country as laborers in construction and light industry (and the way they came to vote just like their Turkish neighbors in Istanbul and elsewhere), Kurdish nationalism in Iraq may well be blunted by the enormous labor migration to the south that is likely to occur over the next two decades. (Further south in the Perso-Arabian Gulf, the countries have such small populations that they have brought millions of guest workers from India, Pakistan, Sri Lanka, Nepal, etc.; but Iraq has a sufficiently large population, including the Kurds, that internal labor migration is likely to be significant).
In any case, Zebari cannot name any real function the US military could play in Iraqi security in the coming decade beyond logistics and air support, and the latter can be done from Qatar. The US is no longer independently and actively patrolling the cities and therefore increasingly lacks the sort of intelligence that would allow a pro-active intervention. The violence is much less now than when the US was wholly in control.
But beyond being biased and incorrect, Zebari is being insubordinate. The Iraqi parliament passed the Status of Forces Agreement which calls for US troops to be out by the end of 2011. That is the decision of the civilian government. For a serving general to attempt to undermine it is a very bad sign, and if there were an Iraqi government in existence, it should fire him.