They rappel down a 65-foot tower, navigate obstacle courses, shoot in the firing range and sleep in pristine barracks. They eat in an air-conditioned mess where brushed aluminum glints from every kitchen surface. Rows of Land Rovers stand by. The entrance reads “The Presidential Guard, Always in Front: Strength, Sacrifice, Redemption.”

One year ago, this 18-acre campus built with $10 million of American taxpayer money was another piece of Jordan Valley desert, and Palestinian guardsmen slept on flea-bitten mattresses and took meals on their laps. Along with a 35-acre, $11 million operations camp a few miles away, also American-financed, it is a real step forward in an otherwise moribund process of Palestinian state-building.

“These guys now feel like they’re on a winning team, that they are building a Palestinian state,” said Lt. Gen. Keith W. Dayton, the American who has been overseeing the training of Palestinian forces, as he watched exercises on Thursday. “And I wouldn’t stay if I didn’t think they were going to do it. I have complete confidence in the Palestinian leadership, and I’m convinced the new administration is serious about this.”

The Obama administration’s envoy to the Middle East, George J. Mitchell, arrived in the region for his second time in a month on Thursday. The secretary of state, Hillary Rodham Clinton, will be here next week. Despite General Dayton’s optimism, no one doubts that they have their work cut out for them. Both the Israelis and the Palestinians are deeply divided, violence and settlement-building continue, and faith in the two-state solution is waning.

But for much of the past year, the Palestinian security forces have trained and increased their role as if all remained on track. Some 1,600 have been through American-financed courses in Jordan. In coordination with Israeli defense officials, Palestinian troops and police officers have taken over much of the patrolling in the West Bank cities of Jenin, Nablus, Bethlehem and parts of Hebron.

Last month, as Israel carried out a war in Hamas-ruled Gaza, some in the Muslim world called on the West Bank to stage a violent uprising in protest. But while there were demonstrations, no such uprising occurred, partly because the Palestinian Authority troops maintained tight order.

All the while, these state-of-the-art facilities were being built, employing hundreds of Palestinian workers. The Presidential Guard College here has been functioning for several weeks, while the National Security Force Operations Camp elsewhere in Jericho will open at the end of next month. Along with police training facilities here supported by the European Union, they represent a new phase in the security plan: sophisticated training under Palestinian command has begun in Palestinian territory.

General Dayton was due to end his three-year assignment, but Mr. Mitchell asked him to stay on for two more years and he has agreed. His decision has been greeted with something approaching jubilation in these camps, where the commanders have come to trust him and to view Washington, through him, as a true ally.

“We have been trained with American money and by General Dayton, and that means a lot to us,” said Brig. Gen. Munir al-Zoubi, commander of the 1,800-man Presidential Guard, the elite force that protects top officials and guests. “We are here to enforce law and order and to use all means to fight terrorism.”

He was asked whether the word “terrorism” was a delicate one.

“Two years ago, we couldn’t talk about or use the term ‘terrorism,’ ” he said. “Any Palestinian who used the term was called a collaborator. But that is no longer true. We have discovered that many people commit terrorist acts under the cover of resistance to occupation. And we are fighting that.”

The big change in those two years has been the Hamas takeover of Gaza and the Palestinian Authority’s hope to turn the West Bank into a model that will reduce the appeal of Hamas.

General Zoubi added that his forces had been trained in human rights, at their request, and in how to shoot without killing when capturing an armed suspect. There are five classrooms for 50 students each on the campus. On Thursday, one of them had a first-aid class going on.

Israeli defense officials say that the development of the Palestinian security forces is a real step forward and that the more the Palestinians do in the West Bank, the less Israel will do. But the Israelis also said that if they did not carry out their night raids on Hamas and Islamic Jihad activists in the West Bank, the area would be a lot less stable.

So there is cooperation. An Israeli officer inaugurated the firing range here, shooting a Palestinian weapon to test it and give his seal of approval. But tensions remain. General Zoubi said new uniforms and protective vests for his men were still waiting at a port in Israel because the Israelis had not released them. And the need for consultation with the Israelis to move his men around frustrates him.

General Dayton is one of the few military men who ply a path between the Palestinian and Israeli officers on a daily basis. He is diplomatic when asked about the tensions.

But his commitment to helping the Palestinians build a responsible and serious security force is enormous. He hopes to have a well-trained battalion based in each of eight West Bank cities when he is through.

He said he first became aware of the importance of this conflict beyond its borders when he was leading weapons searches in Iraq in 2003. As he and his men entered barracks of the Iraqi Republican Guards, he kept seeing drawings on the walls showing Jerusalem’s Dome of the Rock, a sacred Muslim shrine, being strangled by a cobra symbolizing Israel.

At the National Security Forces Operations Camp, still under construction, he met on Thursday with Maj. Gen. Shawki al-Safadi, who has spent his entire adult life wearing the uniform of a Palestinian soldier, starting in 1968 in Jordan, when he was part of the armed wing of the Palestine Liberation Organization.

General Safadi was asked why he turned from an approach of combat to one of coexistence with Israel.

“Anyone can call for peace,” General Safadi responded. “But like General Dayton, I have had a lot of experience. My generation understands the need for peace because we lived under conflict. We were willing to live together in one country. But the Jews want their own homeland. We have come to accept that. And we Palestinians need peace more than any people in the whole world.”