Iraq has seen some increased violence since January, including suicide and car bombings, despite a sharp overall decline in attacks in the past eight months, the Pentagon said on Tuesday.
The rise in violence was partly as a result of recent US-led offensives against Islamist militants, including al Qaeda in Iraq, the Defense Department said in its latest quarterly report on the war.
The release of the report, which covers December through February, coincided with a surge of violence that killed 46 people across Iraq on Tuesday.
The Pentagon noted a rise in security incidents since January in Nineveh and Diyala provinces and other areas where it said al Qaeda in Iraq militants have flocked since being driven from former strongholds by US-allied Sunni tribesmen.
The report called the increased violence a "short term" result of military operations against insurgents that began in January.
Defense officials could not say how closely the violence sparked by the offensives was related to a rise in large bombings that are aimed at causing many deaths, described as "high-profile attacks."
"In January 2008, high-profile attacks rose for the first time in five months as a result of a slight increase in person-borne IEDs (improvised explosive devices) and a slight increase in vehicle-borne IED's," the report said.
Charts of attack data in the report showed the increase in such bombings extending into February with a small rise in civilian deaths for the same period.
No figures accompanied the charts, and many of the comparisons in the report were given in percentages rather than figures.
However, in assessing the overall trend of the war, the report echoed the Bush administration's stance that a US troop increase that started last year has paid dividends by broadly dampening much of the violence in Iraq. Critics of the war opposed the troop increase.
Since June, when the last combat brigade in President George W Bush's so-called surge strategy arrived in Iraq, deaths from sectarian violence have fallen 90 per cent, the report said.
Total civilian deaths were down more than 70 per cent over the same period, the report said, giving only percentages and not actual figures.
"Key indicators are at levels last seen consistently in mid-2005, with indirect fire attacks at levels not seen since early 2004," the report said.
The recent violence underscores the fragility of the relative calm that has taken hold in Iraq, as the Bush administration moves to withdraw its extra combat forces by mid-summer.
There are now 162,000 US troops in Iraq, but the number is expected to fall to about 140,000 by the end of July.
Gen David Petraeus, the top US commander in Iraq, is widely expected to recommend a pause in the troop drawdowns when he testifies to Congress next month.
US officials say attacks have dropped more than 60 per cent because of the US force surge, the emergence of Sunnis allied with the United States against al Qaeda, improvements in the Iraqi army and a cease-fire declaration by radical Shi'ite cleric Moqtada al-Sadr.
But on Tuesday, members of Sadr's militia fought US special forces and Iraqi security forces backed by US warplanes in clashes in which 14 people died. (Reuters)
US report shows increase in Iraq violence since January