WASHINGTON, Jan. 18 (UPI) -- It was another grim week in Iraq, with more massive attacks inflicting casualties on Iraqi civilians and security forces alike, and U.S. fatalities rising again, with little, if any signs of significant progress.

The total number of U.S. troops killed in Iraq through Monday, Jan. 17 since the start of U.S. operations to topple Saddam Hussein on March 19, 2003, was 2,242 according to official figures issued by the Department of Defense, a rise of 33 in only seven days, and an average of 4.7 soldiers killed per day. This was even worse than the figure of 28 in the previous seven-day period when the average death rate was 4 U.S. soldiers killed per day.

These figures unfortunately confirm that the revived high casualty figures of the previous week were no fluke: After more than two-and-a-half years of activity and of Department of Defense and U.S. military studies and implemented plans, the Iraq Sunni insurgency remains undiminished in its lethal capabilities. Contrary to repeated Bush administration predictions, the Dec. 15 parliamentary elections in Iraq did nothing to drain support from the insurgency.

However, the rate at which U.S. soldiers were being injured in Iraq fell very significantly during the same period of time: During the same seven-day period, 52 U.S. soldiers were injured in Iraq, an average rate 7.4 per day.

This was far below the very high figure of 91 U.S. soldiers wounded during the previous seven-day period at an average rate of 13 per day. The number of U.S. troops wounded in action from the beginning of hostilities on March 19, 2003, through Jan. 17, was 16,472, the Pentagon said.

Some 7,625 of those troops were wounded so seriously that they were listed as "WIA Not RTD" in the DOD figures. In other words: Wounded in Action Not Returned to Duty, an increase of 17 such casualties in seven days. In all an estimated 2,000 of the U.S. soldiers wounded in Iraq, or one in eight of them, have suffered brain damage, loss of limbs or been crippled for life by their injuries.

Despite the seriousness of insurgent attacks over the past week, the rate at which U.S. solders were being wounded continued to drop. During the eight day period from Dec. 27 through Jan. 3, 174 U.S. soldiers were injured in Iraq, an average of just below 22 per day, or three times the average daily rate of the past week.

In contrast to the previous week when the insurgents showed their ability to inflict renewed casualties on U.S. military forces and Iraqi civilians alike but took a relative break from their regular high rates of attrition on Iraq security forces, this past week, Iraq security forces and civilians were on the receiving end of ferocious insurgent attacks.

According to the Iraq Index Project of the Brookings Institution, a Washington think tank, 62 Iraq police and troops were killed in the eight-day period from Jan. 9 through Jan. 16, an average rate of 7.75 per day. This was almost double the rate of the previous six day period when 25 Iraqi police and troops were killed from Jan. 3 through Jan. 8, an average of 4.17 per day. And it suggested a return to the high rates of attrition during the seven-day period from Dec. 27 through Jan. 2 when 65 Iraqi police and troops killed, an average of just below 9.3 per day.

The total number of Iraqi police and military killed from June 1, 2003, to Jan. 16, 2005, was 3,977, according to the Iraq Index Project figures. The longer-term monthly trends on Iraqi security forces killed also showed a discouraging rise: For the first half of January through Jan. 16, 108 of them were killed by insurgents. If maintained for the rest of this month, that would give a total casualty figure of around 210-215 Iraqi security forces killed, a significant rise on the 193 killed during December and a rise of more than 15 percent on the 176 killed in November.

From July through November, the number of Iraqi security forces killed per month steadily diminished. But starting in December, that crucial figure has been steadily rising again.

Worse yet, the relatively high figures of Iraqi troops and civilians killed in insurgent attacks over the past week came when they were also succeeding in inflicting an increased number of fatal casualties on U.S. forces.

There were two multiple fatality bombings, or MFBs, during the past eight days, bringing the total for the first half of January through Jan. 16 to 15.

This was in fact a relative lull compared with the onslaught of 14 such attacks in the first eight days of January. But it if maintained, they would still give a sobering average figure of around 30 for the whole month of January, a rise of more than 30 percent compared with the 21 such attacks recorded in December, though still far below the record rates of 46, 39 and 41 MFB attacks in October, November, and December.

In the first 16 days of January, 231 people were killed in these attacks and another 326 wounded. These figures were far worse than for the entire month of December, a period twice as long. Through the 31 days of December, MFB attacks killed 155 people and wounded 174.

According to the Iraq Index Project figures up to Jan. 8, 5,263 people have been killed in MFB attacks since the start of the insurgency and another 10,433 wounded. However, MFB statistics do not include killed and injured in bombings where less than three people were killed.

The project also notes that the U.S. estimate of the number of insurgency combatants killed or captured remains very rough and approximate. The estimates remain 3,000 per month killed for the two months of August and September, but they have been amended downwards to only 2,000 per month for October, November and December.

These figures are curious for several reasons: First, the DOD has reduced its estimate of insurgents killed per month from October through December from 3,000 per month to only 2,000 per month, a reduction of 33 percent per month. The most likely reason for this revision is that the new wave of violence across Iraq in the New Year following the relative lull during the election campaign and immediately thereafter in December led military analysts to reduce their assessments on the level of attrition U.S. and allied Iraqi and Coalition forces were succeeding in inflicting on the insurgents.

But the figures still appear to be "guestimates" rather than estimates: They are still rounded off to a tidy 2,000 per month for three months in a row, neither more nor less. This suggests that specific intelligence even on identifying the number of insurgents killed in sweeps and fire-fights remains extremely imprecise.

Third, even these revised figures may be far too optimistic. If correct, they would mean that the insurgency still lost 12,000 troops in only five months when U.S. official figures cited by the Iraq Index project have put the total number of active insurgents at 15,000-20,000 for the three months of October, November and December.

Those figures, therefore, would -- if true -- mean that the insurgency had lost 60 percent of its active manpower in only five months, a rate of attrition that has only been seen historically in the closing stages of counter-insurgency operations when the guerrilla movement is literally disintegrated and rapidly losing its ability to inflict casualties.

There has so far been no sign of that process so far in Iraq and almost no respected U.S. military analyst believes it is happening. The 2,000 per month revised figure for October through December, like the 3,000 per month figure for August and September, therefore appears to be little more than guesswork.

The cumulative impact of all these figures is that, while the Sunni Muslim insurgency in Iraq has not so far shown signs of dramatically metastasizing in recent weeks, it is back to its old formidable levels and it has remained remarkably impervious to both the broad political strategies and the tactical military initiatives that U.S. political leaders and military commanders have sought to apply against it.