Progress on Syrian cease-fire; Afghan troops rout ISIS wannabes; Russia seeks to overfly US with spy planes; China arms contested islands, ‘just like Hawaii’; and a bit more.

The U.S. and Russia say they’ve reached a “provisional agreement in principle” on a cease-fire in Syria. Now they just have to get their coalition pals and the Syrian opposition on board, Reuters reports. The terms of the agreement are due to be completed in a conversation between U.S. President Barack Obama and his Russian counterpart, Vladimir Putin.

State Secretary John Kerry didn’t elaborate on unresolved issues in the deal, saying Washington and Moscow were “filling out the details” of the agreement—which is believed to lump the al-Qaeda-linked Nusra Front with the Islamic State as far as groups outside of cease-fire restrictions. At any rate, Reuters adds, Kerry said he didn’t expect the deal to lead to any immediate change on the ground.

And on the ground was bloody this weekend, as more than 100 Syrians were killed in car bomb attacks in Homs and the capital of Damascus. The twin attacks “were among the deadliest bombings in government-held areas in Syria’s devastating five-year civil war,” the Associated Press writes. Russia accused ISIS of attempting to derail the peace process in the two attacks.

In case you were wondering: Aleppo is still very much a contested city, and the AP has more from there, here.

Over the weekend, U.S.-backed Kurds in Northeast Syria pushed ISIS out of their last stronghold in the area, the Hasekah provincial town of Shadadi. The town was considered a logistics and command hub for ISIS; and some observers noted the group’s quick retreat from the city as possible evidence of their accelerating decline. But a hasty retreat is not unusual for ISIS anymore, as analyst Hassan Hassan writes. He digs into possible motives and strategies, here.

Oh, by the way: Russia just sent its defense minister to Tehran for talks. This follows a meeting last week where the travel was reversed and Iran’s defense chief reportedly met with both his Moscow counterpart and Vladimir Putin.

The view from Riyadh is not a comfortable one, the Washington Post’s Hugh Naylor reports: “At all levels in Saudi society, including the royal family itself, there is serious concern about our involvement in all these foreign conflicts,” said a prominent Saudi, who elected not to provide his name so that he could live to see tomorrow. “I think there’s a sense that we’ve lost an ability to look at things realistically.” The big fear for the Saudis? That the U.S. doesn’t quite have their back like it did in years past. More here, or read how to prepare for the collapse of the Saudi Kingdom from Defense One contributors Sarah Chayes and Alex De Waal, here.

Afghan troops have pushed ISIS wannabes out of their spot of turf in the east where they were reportedly beheading, kidnapping, beating people and looting whatever they could get their hands on, the Wall Street Journal reported Sunday evening.

Background: “Ground forces—led by the Afghan army and backed by police and paramilitary groups—pushed into Achin district, the group’s main base, just over a week ago as part of a continuing military operation, dubbed ‘Eagle 18.’”

The accelerant: “U.S. airstrikes against Islamic State have intensified since the White House gave the military wider authority to target the group, focusing on Achin. Last Saturday, the Afghan army was able to press into the area and set up outposts along a new front line, pushing the militants toward the mountainous area that borders Pakistan.”

The parties involved included “the Afghan army and various sectors of the police, who coordinated with U.S. forces for close air support. Local militia groups also participated,” the Journal writes. More here.

With Obama not sending more inmates to Guantanamo, what is the U.S. going to do with the militants it takes off today’s battlefields? “Those are questions that worry legal experts, lawmakers and others as U.S. special operations forces deploy in larger numbers to Iraq, Syria and, maybe soon, Libya, with the Islamic State group and affiliated organizations in their sights,” the AP reports in this preview of the White House’s Gitmo closure plan due to Congress this month.

For what it’s worth: Gitmo has about 22 guards and staff for every one detainee, the Miami Herald’s Carol Rosenberg reported this weekend. And the cost per detainee comes out to roughly $4 million. That here.

From Defense One

Tomorrow! The civilian workforce that supports U.S. warfighters is aging. How will the Pentagon attract and retain the next generation? Leaders from DOD, USAF, and DLA will lay out their plans and outlook on Tuesday at 10:30 a.m. EDT, in a livestreamed discussion with Defense One Deputy Editor Bradley Peniston. Register to watch today, here.

Michael Hayden’s defense of drone warfare doesn’t add up. Today, drone strikes are a settled policy in Washington circles, but that does not mean Americans should accept everything a former CIA director says about them, writes the Council on Foreign Relations’ Micah Zenko, here.

Look out, special operators in Syria, the internet has spotted you and that’s a problem. It’s not only the improvement of an airstrip in Northeast Syria that warrants attention, but how it was discovered, write CFR’s Harry Oppenheimer and Aaron Picozzi, here.

Twitter suspensions are muting Islamic State messaging. Researchers found that suspending ISIS sympathizers’ accounts reduced both the size of their networks and the pace of their activity, The Atlantic’s Kaveh Waddell reports.

Welcome to Monday’s edition of the The D Brief, by Ben Watson and Bradley Peniston. And #OTD in 1909: the 16 battleships of the Great White Fleet return to Connecticut after rounding the globe. Here’s a subscription link to send your colleagues: http://get.defenseone.com/d-brief/. Got news? Let us know: the-d-brief@defenseone.com.

China’s island-based missiles in a disputed part of the South China Sea are just like the U.S. military facilities on Hawaii. A Chinese Foreign Ministry spokeswoman put forth that arguable proposition on Monday, Reuters reports, just as Foreign Minister Wang Yi prepared to fly to Washington for a visit.

Meanwhile, reports AP: “The commander of the U.S. Navy’s 7th Fleet said Monday that he is wary of the situation in the South China Sea being painted as a battle between the United States and China, but added the presence of a Chinese missile system on a disputed island will not stop the U.S. military from flying over the region.” That, here.

Germany is said to be mulling a military option in Tunisia. By “military option,” Berlin is considering sending troops to the country for training Tunisia’s security forces on how to handle ISIS, which has established a growing presence in neighboring Libya. More from Agence France-Presse, here.

And speaking of Germany, Chancellor Angela Merkel just ordered an investigation into allegedly covert operations by Russia to weaken the German government and “destabilize the EU,” the Sunday Times reported.

Russia’s U.S. fly-by request. “Russia will ask permission on Monday to start flying surveillance planes [over the United States] equipped with high-powered digital cameras amid warnings from U.S. intelligence and military officials that such overflights help Moscow collect intelligence on the United States,” the AP reported this morning.

The tension: “The request will put the Obama administration in the position of having to decide whether to let Russia use the high-powered equipment on its surveillance planes at a time when Moscow, according to the latest State Department compliance report, is failing to meet all its obligations” under the Open Skies Treaty.

More tension: “The treaty, for instance, obligates each member to make all of its territory available for aerial observation, yet Russia has imposed restrictions on surveillance over Moscow and Chechnya and near Abkhazia and South Ossetia,” said Steve Rademaker, former assistant secretary of state for the bureau of arms control and the bureau of international security and nonproliferation. More here.

And finally: think U.S. intel is in decline? A look through some recently declassified memos may change your mind. Former CIA analyst Aki Peritz, who helped prepare the president’s daily briefings during the Bush and Obama administrations, writes: “The first problem with the 1960s-era PDBs is that they provided mostly tactical, perishable information: This world leader made this speech, that army advanced to that objective, a foreign minister gossiped to our ambassador about something...I also was struck by how little analysis was in this “analytical” product in the ’60s.” Read on at the Washington Post, here.