ISIS-claimed attack in France; US, Russia negotiating cooperation in Syria; Guerrilla-style assaults rise in Iraq; Trump doubles down on NATO shakedown; and a bit more.

Two attackers were shot dead by French police this morning after storming a Catholic church during Tuesday mass in northern France, killing a priest as they took hostages during a short-lived siege in Rouen, about 65 miles northwest of Paris.

French President François Hollande said the attackers claimed to be from ISIS, and the French TV channel M6 reported one of the men “was on the French government’s terror watch-list, known as the S list,” according to the BBC. One of the hostages—which included two nuns and two churchgoers, in addition to the slain priest—remains in critical condition, according to the Interior Ministry.

Coming in seven to 10 days: The U.S. aims to unveil its military cooperation plan with Russia in the Syrian war, State Secretary John Kerry said after discussions with his Moscow counterpart on the sidelines of a meeting of Southeast Asian nations in Laos, Reuters reports this morning.

Kerry: “My hope would be that somewhere in early August — the first week or so, somewhere in there — we would be in a position to be able stand up in front of you and tell you what we're able to do with the hopes that it can make a difference to the lives of people in Syria and to the course of the war,” Kerry told reporters in the capital Vientiane.

What’s known so far: “The proposal envisages Washington and Moscow sharing intelligence to coordinate air strikes against the al Qaeda-affiliated Nusra Front and prohibit the Syrian air force from attacking moderate rebel groups.”

Word of the deal’s progress follows cautious remarks Monday from U.S. Defense Secretary Ash Carter, speaking to reporters alongside Chairman of the Joint Chiefs, Gen. Joseph Dunford. “We had hoped that they would promote a political solution and transition to put an end to the civil war, which is the beginning of all this violence in Syria, and then combat extremists rather than moderate opposition, which has to be part of that transition,” Carter said. “So they’re a long way from doing that.”

The Associated Press writes of Monday’s meeting at the Pentagon that “a reporter told Carter that he sounded unenthusiastic about the Kerry effort.” Carter’s reply: “No, I’m very enthusiastic about the idea of the Russians getting on side and doing the right thing. And I think that would be a good thing if they did. I think we're a ways from getting that frame of mind in Russia. But that’s what Secretary Kerry is working toward.”

Dunford’s caveat: “We’re not entering into a transaction that is based on trust,” he said. “There will be specific procedures and processes in any transaction that we might have with the Russians that would account for protecting our operational security.” More on that angle from Military Times, here.

Meantime in Syria, Assad’s army has sent a text message to residents of rebel-held east Aleppo asking them to help push “mercenaries” out of the city while also promising safe passage to those eastern residents who elect to flee the city ahead of an upcoming offensive, Reuters reports from state-run SANA news.

Also this morning, government troops have “seized a rebel-held neighbourhood on the northwest outskirts of Aleppo, tightening their siege of the opposition-held parts of the city,” AFP reports. “The Britain-based Syrian Observatory for Human Rights said loyalist troops had full control of the Leramun district after heavy clashes, and reported fighting for neighbouring Bani Zeid, which is also held by rebels. The two areas have been used by rebels to launch rockets into government-held districts in the west of the city.”

News of the advance follows recent reports that Assad’s “forces effectively severed the opposition's Castello Road supply route on July 7, when they advanced to within firing range. They have tightened the encirclement of the rebel-held east since then, taking parts of the road itself and prompting food shortages and spiralling prices in opposition neighbourhoods.” Regime barrel bombs also reportedly killed a dozen residents of Aleppo on Monday.

And about 220 miles south in the capital of Damascus, a car bomb detonated near an Iranian school on Monday, with casualties reported but specific numbers are so far unavailable. More here.  

Do we need more signs that ISIS is on the defensive? We get one big indication anyway, and it comes in the form of growing guerrilla-style attacks across key population centers—particularly around Baghdad, The New York Times reports off feedback from American diplomats and commanders. “Already, officials say, many Islamic State fighters who lost battles in Falluja and Ramadi have blended back into the largely Sunni civilian populations there, and are biding their time to conduct future terrorist attacks. And with few signs that the beleaguered Iraqi prime minister, Haider al-Abadi, can effectively forge an inclusive partnership with Sunnis, many senior American officials warn that a military victory in the last urban stronghold of Mosul, which they hope will be achieved by the end of the year, will not be sufficient to stave off a lethal insurgency.”

The mid-term implications: “A return to guerrilla warfare in Iraq, while the United States and its allies still combat the Islamic State in Syria, would pose one of the first major challenges to the next American president, who will take office in January. American public opinion has so far supported President Obama’s deployment of roughly 5,000 troops to help Iraq reclaim territory it lost to the Islamic State in 2014, but it is not clear whether political support would dissipate in a sustained effort to fight insurgents.”

Said the Iraqi officer in charge of the Falluja clearance op, Lt. Gen. Abdul Wahab al-Saidi: “We have hurt ISIS’ morale, but nobody can deny that ISIS still has its sleeper cells, and we expect anything from it.” More here.

From Defense One

Trump’s NATO-rattling interview has delayed a key evolution in U.S. nuclear posture. The Obama administration had been working to reassure nervous allies ahead of renouncing any first use of nuclear weapons. Now that's on hold, writes Stimson Center co-founder Michael Krepon, here.

Welcome to Tuesday’s edition of The D Brief by Ben Watson and Bradley Peniston. On this day in 1861, Gen. George McClelland took over the Army of the Potomac in the wake of defeat at the first Battle of Bull Run. Send your friends this link: And let us know your news:

A “major offensive” is under way today to quash IS in eastern Afghanistan, AP reports. “The offensive began over the weekend in Nangarhar province, where the IS group has had a presence for the past year, said Dawlat Waziri, spokesman for the Defense Ministry. The offensive, part of the government's Operation Shafaq — or Dawn in Pahsto— started hours after an IS suicide bomber killed at least 80 people who were taking part in a peaceful demonstration in Kabul on Saturday.”

President Ashraf Ghani ordered the op, “which Waziri said will consist of airstrikes and ground attacks, including those by special forces. Clean-up operations aimed at ensuring that IS loyalists do not return to the area would follow.” More here.

The U.S. is mulling counterterrorism cooperation with China, “including information exchanges and helping bring stability to places like Iraq,” an unnamed White House official told Reuters this morning following National Security Advisor Susan Rice’s recent visit to China. That, here.

U.S. to China: THAAD is aimed only at North Korea—not you. That one over here.

“Things are getting very weird,” writes Talking Points Memo, noting that 1) GOP 2016 contender Donald Trump is doubling down on his mercantile approach to NATO, telling a rally crowd in North Carolina on Monday night that “We have to walk... Within two days they’re calling back! ‘Get back over here, we’ll pay you whatever the hell you want.’” and 2) when the Washington Post asked the Russian officials about their alleged involvement in the theft and publication of Democratic Party emails, a Kremlin spokesman replied by citing a Trump family member: “Mr. Trump Jr. has already strongly responded.”

Also on Monday, Democratic challenger Hillary Clinton took numerous swings at Trump, “calling his policies dangerous and his outlook poisonous,” Military Times reports. Trump speaks at the Veterans of Foreign Wars annual convention today.

Lastly today: Two U.S. Army female officers hope to become the first to earn the Special Forces “long tab,” Stars and Stripes reports. “The women are the first female soldiers to be accepted into the Special Forces Assessment and Selection and could report to the three-week program at Fort Bragg, North Carolina as early as October, said Maj. Melody Faulkenberry, a spokeswoman for the Army’s John F. Kennedy Special Warfare Center.” But we won’t learn their names for some time yet since officials said “it could possibly change the way they are treated … or add undue pressure on them in a course that is already very demanding.” More here.