U.S. Defense Secretary Donald H. Rumsfeld urged Iraq's new leaders Tuesday to push full-speed ahead in developing a constitutional government and defeating the insurgency.

"Anything that would delay that or disrupt that as a result of turbulence or incompetence or corruption in government would be unfortunate," Rumsfeld said before he began a round of talks with Iraqi leaders.

This week's trip to Iraq was Rumsfeld's second in three months.

The newly designated prime minister, Ibrahim al-Jaafari (search), told reporters after meeting Rumsfeld at his official residence that he realized the risk of setbacks in the political process.

"I don't deny there are challenges, but I am sure we are going to form very good ministries," he said in English. He predicted that the government bureaucracy would be staffed by "good technocrats" from a variety of backgrounds.

Rumsfeld met separately with Interim President Jalal Talabani (search), the Kurdish former rebel leader.

Meanwhile, the Iraqi government said Tuesday it captured a former member of Saddam Hussein's regime who was believed to be funding the insurgency.

The government said in a statement it captured Fadhil Ibrahim Mahmud Al-Mashadani (search) at a farm northeast of Baghdad. It said he worked as the former leader of the military bureau in Baghdad under Saddam.

The statement said al-Mashadani was a high-ranking member of Saddam's Baath Party and was "among the main facilitators of many terrorist attacks in Iraq."

"Mashadani is believed to be personally responsible for coordinating and funding attacks against the Iraqi people," the statement said.

Lost in Translation

In a joint appearance before reporters after their meeting, Rumsfeld and Talabani struggled to make themselves understood to a mixed Iraqi-American press corps.

At one point, Talabani translated for Rumsfeld as the defense secretary fielded a question from an Iraqi speaking in Arabic.

After hearing Talabani's version of the question, Rumsfeld accused the reporter of phrasing it inaccurately, and the garbled exchange ended abruptly as another Iraqi posed another question.

Speaking in English, Talabani said he had assured Rumsfeld that Iraq's interim leaders will work together.

"We are planning to have the [permanent] government as soon as possible, but you know this is the beginning of democratization in Iraq," Talabani said, adding that he expects the government to complete its selection of cabinet ministers before the end of this week.

The next major goal is to have a new constitution written by August and ratified by a national vote in October.

Rumsfeld also held a closed meeting with Gen. George Casey (search) and Lt. Gen. John Vines (search), the top two American commanders in Iraq.

In a brief interview with reporters later, Casey said he was encouraged that the long and difficult process of training and equipping Iraqi security forces was gaining ground.

"We're getting better and more efficient at it," he said.

The Iraqis, in turn, have gained a new measure of confidence since the Jan. 30 elections.

"Iraqi security forces are operating more aggressively" against the insurgents, Casey said.

Meanwhile, outgoing interim Prime Minister Ayad Allawi has asked Casey to review the portfolios of Iraqi detainees, arguing that many remain in custody even though they don't face formal charges, his office said Tuesday.

In a letter to Casey, Allawi specifically mentioned several followers of Shiite cleric Muqtada al-Sadr (search) and a large number of Sunni imams, the statement said.

"Resolving such issues will play a big role in consolidating national unity ... and in making the citizens believe in the government's good intentions to provide security and stability for all Iraqis," the statement said.

The Rumsfeld meetings come as U.S. military commanders said this week that they expect American troop levels to drop to about 100,000 by early next year, depending on the persistence of the insurgency and local security-force training, defense sources confirmed to FOX News.

"We're hitting our goals," one senior U.S. commander told FOX News, adding that the military did not want to be overly optimistic about developments in Iraq but they are very excited about progress being made there.

Rumsfeld also gave a pep talk to a few hundred soldiers at Camp Liberty, headquarters of the 3rd Infantry Division. He also pinned Bronze Star medals and Purple Heart awards on several soldiers and participated in a mass re-enlistment ceremony for about 100 soldiers gathered in a mess hall.

"The role you're playing is a critically important role in the global war on terrorism" he told them.

Rumsfeld arrived in the Iraqi capital before sunrise aboard an Air Force C-17 cargo plane for his second visit in three months. It was his ninth visit since the war began in March 2003.

The frequency of his visits in recent months reflected a desire to push the political and military momentum that Rumsfeld believes has been growing since the Jan. 30 elections for a national assembly.

En route from Washington, Rumsfeld told reporters he would press the new Iraqi leadership to avoid delays on either the political or security front at a time when U.S. troops are still being killed or wounded and billions of U.S. taxpayer dollars are being invested in rebuilding the country.

"It's important that the new government be attentive to the competence of the people in the ministries and that they avoid unnecessary turbulence," Rumsfeld said.

Some in the Bush administration are concerned that factional maneuvering during the formation of the transitional government could undermine the counterinsurgency effort that is a key to eventually pulling U.S. troops out of Iraq.

Meanwhile, President Bush (search) will visit U.S. troops and families at Fort Hood in Texas on Tuesday. He's expected to thank them for their sacrifices, praise their accomplishments and hail the progress of Iraq's steps toward democracy and freedom, including the naming of Talabani and al-Jaafari as the interim president and prime minister, respectively.

Among the coalition forces that rapidly moved through Iraq two years ago to bring about the end of Saddam Hussein's regime were U.S. Army troops of the First Calvary and Fourth Infantry Division out of Fort Hood.

The soldiers of the First Calvary Division have since been heavily involved in helping secure Iraq from insurgents on three fronts: fighting enemy warriors on the streets of Sadr City in Baghdad, helping the Iraqi citizens with humanitarian needs and training Iraqi police and security forces.

Bush will have lunch with the troops, then meet about 30 families of soldiers killed in Iraq and Afghanistan.

FOX News' Kelly Wright and The Associated Press contributed to this report.