American military deaths for July rose to 73 on Tuesday with the report of a Marine killed in combat, but the toll was still the lowest in eight months as the US said it was gaining control of former militant strongholds. By contrast, July was the second-deadliest month for Iraqis so far this year, according to an Associated Press tally. US military officials, while saying they were heartened by the downturn in American deaths, cautioned it was too early to predict a sustained trend. "We had said over the summer it's going to get harder before it gets easier," said Lt. Col. Christopher Garver, a military spokesman in Baghdad. "We're hoping that we're in the easier part, but we still obviously have a long way to go." Nevertheless, the daily average for U.S. troop deaths in July was at least 2.35 - higher than the daily average of 2.25 last year, and remarkably consistent with average daily casualties in 2005, at 2.32, and 2004, at 2.33. This was also the deadliest July for US troops since the war began. For the previous three years, the month of July saw a relatively low death toll. In July 2006, 43 US troops were killed in Iraq, and 54 died in each of the previous two Julys. The Defense Department, meanwhile, announced Tuesday that nearly 20,000 US troops based in the United States will begin leaving for Iraq in December for a regular rotation of combat forces. The incoming units from the Army and Marine Corps are not part of the US troop buildup announced by President Bush in January, Pentagon spokesman Bryan Whitman said. All of the so-called "surge" forces arrived by mid-June. Separately, an Apache helicopter went down Tuesday after taking ground fire in a predominantly Shiite area in eastern Baghdad, but both crew members were safely evacuated, the military said. Also, two unmanned drones have crashed this week at the Balad air base north of Baghdad, the military said. More than 100 American forces died each month in the April-to-June period as the incoming US troops were deployed with the Iraqi army in Baghdad's dangerous streets and security outposts. The forces also moved to clear areas that had been militant safe havens in regions around Baghdad and to Baqouba, the insurgent and militia stronghold northeast of the capital. American officials credited the drop in US casualties with the new strategies put in place by commander Gen. David Petraeus, who has taken the fight to the enemy rather than keeping forces in defensive bases. "We're chasing them to areas where they're not so well prepared and they don't have time to prepare, so chances are we will have fewer casualties," a senior US military official said, speaking on condition of anonymity because he was not authorized to comment on the sensitive operations. "The tactical momentum has shifted to us." The No. 2 commander in Iraq, Lt. Gen. Ray Odierno, expressed cautious optimism last week about the decline in deaths. He said casualties had increased as US forces expanded operations into militant strongholds in the initial stages of the five-month-old security crackdown to clamp off violence in Baghdad. Now, he said, casualties were dropping as Americans gained control in those areas. The US military said Tuesday that the Marine had been killed the day before in fighting in the vast Anbar province west of Baghdad. The attack raised to at least 73 the number of US service members who have died in Iraq in July, the lowest number since November 2006, when at least 70 US deaths were reported. In all, at least 3,652 members of the US military have died since the Iraq war started in March 2003, according to an AP count. The figure includes seven military civilians. Iraqi deaths rose, with at least 2,024 civilians, government officials and security forces killed in July, about 23 percent more than the 1,640 who died violently in June, according to AP figures compiled from police reports nationwide. That made July the second-deadliest month for Iraqis so far this year; at least 2,155 Iraqis were killed in May. The figures are considered only a minimum based on AP reporting. The actual number is likely higher, as many killings go unreported or uncounted. At least 32 Iraqis were killed or found dead on Tuesday, including 25 bullet-riddled and tortured bodies in Baghdad and the southeastern city of Kut. President Bush's choice to head the Joint Chiefs of Staff said Tuesday an increase of troops in Iraq is giving commanders the forces needed to improve security. "Security is better, not great, but better," said Navy Adm. Michael Mullen, speaking before the Senate Armed Services committee at his nomination hearing. Bush chose Mullen to replace Marine Gen. Peter Pace. However, Mullen acknowledged under questioning that "there does not appear to be much political progress" in Iraq. "I believe security is critical to providing the government of Iraq the breathing space it needs to work toward political national reconciliation and economic growth, which are themselves critical to a stable Iraq," Mullen said. "Barring that, no amount of troops and no amount of time will make much of a difference." In political developments, Iraqi President Jalal Talabani, a Kurd, began a last-minute effort Tuesday to save the Shiite-dominated government from possible collapse, pressing key Sunni Arab politicians to set aside threats to quit the Cabinet and counseling the prime minister to "seriously consider" their demands. Talabani also warned of "negative consequences" if the six Cabinet ministers from the Iraqi Accordance Front were to leave al-Maliki's 14-month-old government, as it has threatened to do on Wednesday. He did not elaborate, but the withdrawal of the Accordance Front's ministers could erase the government's "national unity" status and diminish its legitimacy. The leader of Iraq's autonomous Kurdish region, Massoud Barzani, also warned Tuesday of a "real civil war" if the central government does not implement a constitutional clause on the future of Kirkuk, the oil-rich city claimed by the Kurds. Control over Kirkuk and the surrounding oil wealth is in dispute among the city's Kurdish, Arab and ethnic Turkish populations. Nationally, the dispute pits the Kurds, who want to annex it to their autonomous region in northern Iraq, against the country's Arab majority and its small minority of Turks, known locally as Turkomen.