By LINDSAY WISE

Tribune News Service

WASHINGTON -- Republican Sen. Pat Roberts returned Monday from a clandestine trip to Iraq to visit Kansas soldiers, bringing with him a new-found support for a U.S. military mission he previously criticized for being "much too vague" and dependent on foreign partners.

American troops and their allies in Iraq are making "real and tangible progress" against Islamic State militants who seized much of Iraq and Syria during the summer, the Kansas senator said in a press call with reporters after his plane landed in Washington.

"I am guardedly optimistic that Iraqis can take the necessary steps to take back their country," he said.

Roberts, 78, secretly traveled to Iraq and Kuwait for five days at the invitation of Major Gen. Paul E. Funk II, commander of the Kansas-based 1st Infantry Division of the U.S. Army.

Approximately 500 troops from the headquarters unit of the division -- nicknamed the "Big Red One" -- deployed two months ago from Fort Riley to assist Kurdish Peshmerga fighters and the Iraqi military in their fight against the Islamic State.

In addition to visiting troops in Irbil and Baghdad, Roberts met with the new prime minister of Iraq, Haider al Abadi; Iraq's defense minister, Gen. Babakir Zebari; and foreign minister, Ibrahim al Jaafari. The senator also met with the U.S. ambassador in Kuwait, Douglas Silliman.

Roberts said he was "very impressed" with al Abadi. "He's certainly an improvement over the last prime minister," Nouri al Malaki, Roberts said.

Government corruption seems to be diminishing under al Abadi's leadership, he said, and new attempts are underway to reconcile between Sunni and Shia in Iraq.

Roberts said he was especially encouraged to see Iraqis taking the lead role in command centers, where he said he witnessed Iraqis and Kurds all working together.

On the last day of the senator's visit, Kurdish fighters backed by U.S. airstrikes took back Mount Sinjar from the Islamic State.

Under the leadership of Kansas' Big Red One, Roberts said, Kurdish fighting forces killed a great many Islamic militants and sent the survivors fleeing back to Syria.

"It was a big win," he said.

Roberts, a former Marine captain, has been a vocal critic of President Barack Obama's strategy to battle the Islamic State.

"I am deeply concerned that the president's plan is focused on the long-term solution and fails to address the immediate need to stop ISIS in its tracks and turn back its cancerous spread throughout the region," he said in a statement in September.

On Monday, however, Roberts said he's now much more confident in that strategy, though he complained the administration has done a poor job of selling the U.S. mission in Iraq to Congress and the American people, who are war-weary.

"The president needs to do a better job of explaining what it is he's asking us to support," he said Monday.

"I know the commanders in the field know it and believe it, but we don't hear much from the White House."

Roberts no longer sees a need for a formal declaration of war against the Islamic State, which would require approval from the Senate.

"I think that's probably an issue that has passed," he said. "We do authorize training and assistance. If you authorize that, we are not actually taking part with boots on the ground in a war. I know I originally thought, being a Marine, that would not be the answer, but having seen Sunni and Shia and everyone else (working together) and seeing the routing of (the Islamic State) ... I don't think an act of war at this point is needed."

Roberts said he was "really shocked" to learn he was the first senator to visit Iraq in 18 months.

"That's just not right," he said.

Roberts said he would encourage his colleagues in Congress to make their own visits to Iraq to see the progress for themselves.

"Right now," he said, "this strategy is working."