Situation Report: U.S. launches fresh attempt to end Syrian civil war; Iran’s conservative media grows critical of the nuclear deal; U.S. warplanes arrive in Turkey; New Afghanistan violence; and more.

By David Francis and Adam Rawnsley

Let’s talk. Washington has launched a fresh effort to restart peace talks to end the four-year-old Syrian civil war, FP’s Dan De Luce reports. The White House is trying to piggyback on the success of Iran nuclear negotiations, as well as the Damascus regime’s battlefield setbacks.

A note of caution: Initial efforts, led by Secretary of State John Kerry, could end in failure, according to U.S. officials. There are deep divides between the main players and their patrons that need to be bridged. Officials also said there’s no specific timetable to settle negotiations.

Iran looms large. It’s the primary backer and lifeline for Syrian strongman Bashar al-Assad. U.S. officials had been reluctant to engage Tehran on Syria; they didn’t want to give Iran a possible point of leverage in the nuclear talks.

Did a window open? Now that the nuke talks are settled, U.S. officials see an opportunity to use diplomacy to end the conflict, which has claimed more than 200,000 lives while sending Syrians fleeing to other countries. Check out the full report here.

Familiar problems. Last week, FP’s John Hudson reported that representatives of the P5+1 group gathered on Capitol Hill to rally support for the nuclear accord among Senate Democrats. Now, the Wall Street Journal’s Aresu Eqbali and Asa Fitch report the deal is also getting a skeptical reception by some in Iran. Criticism by conservative media there is growing as their liberal counterparts continue to insist the deal is a good one.

American F-16s arrive in Turkey. A small detachment of six F-16 “Fighting Falcons,” support equipment, and about 300 personnel arrived at Incirlik Air Base to support Operation Inherent Resolve. The jets were deployed after Turkey acquiesced and agreed to allow the United States to use the strategically important base. Turkish media reported that about 30 planes are expected to join the fight, according to the Associated Press.

A wave of violence in Afghanistan continues. On Friday, elite U.S. forces and Afghan army and police were targets of attacks in Kabul that left at least 65 people dead. Now, the New York Times’s Najim Rahim and Mujib Mashal report at least 29 people were killed and 19 others hurt in a suicide bombing aimed at a militia in the northern province of Kunduz. The Taliban has been escalating attacks following the death of the group’s leader, Mullah Mohammad Omar, at the end of July.

Happy Monday, all. I’ll be pinch-hitting while SitRep chief Paul McLeary has the week off for some well-deserved relaxation and fun, or a close approximation thereof. For those of you who aren’t fortunate enough to be on vacation this week, please direct any tips, notes, or otherwise interesting bits of information to david.francis@foreignpolicy.com, or get social with us on Twitter: @davidcfrancis or @arawnsley

China

The Chengdu J-10B, China’s update to its workhorse multirole J-10 fighter jet, might have to be powered by Russian technology if the People’s Liberation Army Air Force wants it to get off the ground. The Taihang engines China had planned to use can’t provide the maneuverability the J-10B needs, and so it’s reportedly looking at Russian AL31FN-S3 engines to equip the fighters.

Business of defense

Last week, France ditched its deal to sell two copter-carrying Mistral class ships to Russia, handing back a roughly $860 million deposit. The cancellation came as part of the U.S. and Europe’s larger campaign to spurn Russia in the wake of its invasion of Ukraine and annexation of Crimea. But now that it’s got two extra mint-condition Mistrals on its hands, France is looking for new buyers. At the moment, Egypt, with the encouragement of Saudi Arabia, is reportedly interested in buying the ships. Other rumored shoppers include Canada, Egypt, India, and Singapore.

Who’s #1?

The hot question of the summer for senior national security officials is: What’s the biggest threat to the United States? U.S. News & World Report‘s Paul Shinkman rounds up the responses of Joint Chiefs in waiting, who — with the exception of soon-to-be Marine Commandant Lt. Gen. Robert B. Neller — pick Russia for its recent aggression in Eastern Europe. By contrast, the White House tends to cite the Islamic State. Who’s got the right answer? Maybe the question doesn’t really capture the complexity of national security policymaking right now, says former Obama and Bush administration adviser Barry Pavel. “We can’t say, ‘This one is more important than that one.’ We have to address five or six threats.”

North Korea

South Korea has pledged to resume propaganda broadcasts along the north-south border for the first time since 2004. The policy change comes after landmines injured two South Korean soldiers on the southern side of the demilitarized zone last week. The United Nations Command, led by the United States, blamed North Korea for the incident, citing it as a violation the 1953 armistice that ended the Korean War. South Korean officials speaking to the Associated Press also floated the potential for other, unspecified forms of retaliation against the North.

Don’t expect the recent U.S.-Iran nuclear diplomacy to rub off on North Korea, warns former CIA deputy director John McLaughlin in a new piece at Ozy.com. America’s leverage against the Kim dynasty is less than it used to be, and North Korea isn’t in quite the same circumstances as Iran. McLaughlin writes that the North’s nuclear program is too far along and its international isolation already so severe that a U.S.-North Korea Joint Comprehensive Plan of Action just isn’t in the cards right now.

Iran

Nothing to see here, just a bit of long overdue roadwork. That was Iran’s response to a report out of the Institute for Science and International Security (ISIS), a nonproliferation think tank that produced satellite imagery last week showing increased activity at the Parchin military complex, which has long been suspected as the scene of clandestine nuclear weapons work by Iran. ISIS suggested the activity could be a sign Iran’s trying to hide evidence in advance of upcoming inspections. Iran’s Foreign Affairs Minister Javad Zarif brushed off the accusations, saying the activity was simply the result of “road construction.”

Iraq

Ever since the Islamic State recaptured Mosul and drew the United States back into another military campaign in Iraq, American forces have had been tense, awkward frenemies with Iraq’s Shiite and often Iran-backed militias. But now that relationship has gotten tenser, according to an account from Missy Ryan at the Washington Post. The story fleshes out an earlier Bloomberg piece about U.S. troops and Shiite militias sharing the Taqaddum Air Base in eastern Anbar province. Ryan reports that American troops shared the base with 30-50 members of Kata’ib Hezbollah, an Iranian-backed and State Department-designated foreign terrorist organization, but only after negotiating a loose quarantine of Kata’ib Hezbollah to another part of the base. With battle lines in Iraq constantly shifting, putting distance between U.S. and Iranian-backed forces might not be so simple. “As the geography and the battle space changed, so has our level of concern,” one senior defense official told the Post.

It’s complicated.

The Kurdish People’s Protection Units, known as the YPG, has made big gains against the Islamic State. But according to the New York Times’s Rukmini Callimachi, members of the group are wary of Turkey’s growing involvement in the war. Turkish planes have begun bombing mountain camps of the Kurdistan Worker’s Party, or PKK, a YPG ally.

Tunisia

The New York Times’s Carlotta Gall takes a look at how affiliation with Islamic State has changed the tactics of Tunisian jihadist groups. More and more young Tunisians have gone to fight alongside the group in Libya. As they return home, their relationships and experiences have shaped patterns of terrorist violence in Tunisia. What had once been a small group of militants engaged in sporadic attacks against security forces in remote areas appears to changing into a larger, more aggressive group of jihadists operating in the heart of the country and targeting foreign tourists.

Think tanked

SitRep got a sneak peak at a new National Security Network (NSN) report set for release today, which examines the F-35’s capabilities against the range of likely contingencies and adversaries the Pentagon expects it to encounter. Using Joint Chiefs Chairman Gen. Joseph Dunford’s review of F-35 fleet size as a pivot point, the report, by NSN’s Bill French and Daniel Edgren, argues that the jet is inadequate in air-to-air engagements both within and beyond visual range, lacks the range necessary to take on anti-access threats in the Asia Pacific region, and is overmatched in counterinsurgency campaigns.