Gen. Joseph F. Dunford Jr. chairman of the Joint Chiefs of Staff, right, speaks at a news conference at the Pentagon with Defense Secretary Jim Mattis, center, and special presidential envoy Brett McGurk. (Win Mcnamee/Getty Images)

The Pentagon has stepped up communication with the Russian military over Syria, a top official said Friday as the Trump administration lays plans for future operations likely to thrust U.S. forces closer to Russian and Syrian troops.

Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff, said that the United States had opened a new channel between senior U.S. and Russian military officials to discuss what Pentagon officials refer to as the “deconfliction” of ground and air operations within Syria.

The United States is now in the third year of its campaign against the Islamic State in Syria, where the application of Russian military might has strengthened the hand of President Bashar al-Assad.

“I’m confident that we’ve made progress in that regard over the last couple months,” Dunford told reporters at the Pentagon.

“My sense is that the Russians are as enthusiastic as we are to deconflict operations and ensure that we can continue to take the campaign to ISIS and ensure the safety of our personnel,” he said, using another name for the Islamic State.

The United States has sought mostly to limit its involvement in Syria to operations against the extremist group, hoping to avoid being pulled into the larger civil conflict. It has done so, in part, by focusing on areas such as Raqqa, the group’s de facto capital, where the Syrian government has little military presence.

Dunford suggested that communication with Russia would become more important as the United States looks beyond an upcoming offensive to recapture Raqqa toward operations in places like Deir al-Zour, an eastern city where both the Islamic State and Syrian government are active.

The preview of future offensives comes as the Trump administration seeks to highlight the progress it has made in combating the Islamic State.

At a news conference focusing on that campaign, senior U.S. officials said the group had lost about 23,000 square miles of territory under its control since the peak of its power in 2014.

Speaking alongside Dunford, Defense Secretary Jim Mattis said that President Trump has approved a series of measures to expedite the group’s defeat.

Among those steps, Mattis said, is a new emphasis on encircling and cutting off the Islamic State in population centers, rather than positioning local forces around cities in a way that could allow militants to escape and regroup elsewhere.

“By taking the time up front to surround these locations, instead of simply shoving them from one to another . . . based on the recommendation that we made and the direction that President Trump took, we now take the time to surround them,” Mattis said.

“Foreign fighters are the strategic threat, should they return home to Tunis, to Kuala Lumpur, to Paris, to Detroit, wherever,” he said. “So by taking the time to deconflict, to surround and then attack, we carry out the annihilation campaign so we don’t simply transplant this problem from one location to another.”

Mattis said Trump had also delegated decision-making “to the right level to aggressively and in a timely manner move against enemy vulnerabilities.”

Defense officials said that those measures had been approved several months ago. The delegation of authority would permit military commanders to send troops closer to the front lines in a wider array of situations than had occurred previously, said one official who spoke on the condition of anonymity to discuss sensitive military strategy. In Iraq, the Obama administration had already authorized the U.S. troops to operate with local forces at the battalion level in some situations.

The Trump administration, in a break with practice under President Barack Obama, has quickly moved to shift responsibility for tactical decisions on a range of issues from the White House to the military.

“No longer will we have slowed decision cycles because Washington, D.C., has to authorize tactical movements on the ground,” Mattis said, referring to the Islamic State fight.

Dunford’s remarks regarding Russia come as the administration confronts a snowballing controversy over the Trump camp’s alleged ties to Russia.

While Trump has displayed a friendly stance toward Russian officials at times, his administration has also blasted Moscow over its support for Assad. Last month, Trump authorized a series of missile strikes on Syrian government targets after a chemical attack that officials suggested was covered up with the help of Russia.

While Dunford said military coordination was prohibited by U.S. law, he said expanded communications would be helpful as the areas where U.S. troops and aircraft operate become “increasingly complex and constrained.”

Under the recently established channel, the official responsible for planning future operations on the Joint Staff, Lt. Gen. Kenneth F. McKenzie Jr., routinely talks to his Russian counterpart, Dunford said.

In another illustration of U.S.-Russian dialogue, Dunford said that he spoke Thursday with Valeriy Gerasimov, the chief of the general staff of Russia’s armed forces.

“We are looking for the Russians to work with the regime, to deconflict our operations,” Dunford said.

The current arrangement did not appear effective as recently as Thursday, when U.S. officials asked Russia to steer forces affiliated with the Syrian government away from an air base manned by U.S. Special Forces and Washington-backed rebel groups. When the pro-government forces did not respond, U.S. aircraft ultimately launched an attack on some of them.