4 North Korean launches; Waves of car bombs in Mosul; China crashes US airpower conference; America can’t agree on its main threat; and just a bit more...

North Korean provocation. North Korea launched “four ballistic missiles into the sea off Japan's northwest on Monday, angering South Korea and Japan, days after it promised retaliation over U.S.-South Korea military drills it sees as a preparation for war,” Reuters reports this morning. “The missiles flew on average 1,000 km (620 miles) and reached a height of 260 km (160 miles).” They “were launched from the Tongchang-ri region near the reclusive North's border with China,” South Korean military spokesman Roh Jae-cheon told reporters.

The missiles landed in the sea between Japan and the Korean Peninsula, the Washington Post reported. “These missile launches clearly show that North Korea has developed a new threat. We will collect information and strongly protest to North Korea,” Japanese Prime Minister Shinzo Abe said in response.

On the timing: The launches “coincided both with joint U.S.-South Korean military exercises on the southern half of the peninsula and with the opening of the annual National People’s Congress in China,” writes the Post.

A bit more on those U.S.-South Korean drills: they involve "more than 320,000 South Korean and U.S. troops and high-tech U.S. firepower...They began last week and will continue through the end of April."

Adds the Post: "In the past year or two, the exercises have become more overtly offensive, with the two militaries practicing ‘decapitation strikes’ on the North Korean leadership."

Mapped: potential ranges of North Korean missiles, via The New York Times’ Troy Griggs, here.

Your Monday #LongRead: The Pentagon has been trying to secretly disrupt North Korean missile launches for years, the Times’ David “Stuxnet” Sanger  and colleague William Broad reported this weekend: "Three years ago, President Barack Obama ordered Pentagon officials to step up their cyber and electronic strikes against North Korea’s missile program in hopes of sabotaging test launches in their opening seconds. Soon a large number of the North’s military rockets began to explode, veer off course, disintegrate in midair and plunge into the sea. Advocates of such efforts say they believe that targeted attacks have given American antimissile defenses a new edge and delayed by several years the day when North Korea will be able to threaten American cities with nuclear weapons launched atop intercontinental ballistic missiles."

But hold your horses, he writes, because “other experts have grown increasingly skeptical of the new approach, arguing that manufacturing errors, disgruntled insiders and sheer incompetence can also send missiles awry." Full story, here.

Iraqi troops fought off “waves” of car bombs in Mosul this weekend as they seized a second Tigris River bridge that “leads to the Islamic State-held old city center from the south,” Reuters reports this morning as troops push closer into the group’s last corners of the city. (Map: here are the districts that remain in ISIS hands.)

After sending six car bombs at Iraqi troops on Sunday, ISIS sniper and mortar teams began scurrying house-to-house in the Shuhada and Mansour neighborhoods while federal police closed in on that main government complex—at last check, some 500 meters away, AP reported.

Reuters posted pictures of a “brutal street battle”—with families fleeing, soldiers taking cover behind the burnt husks of cars, special forces storming alleys and stairwells, and Mosul citizens being searched for possible suicide belts.

About those car bombs: Here are some of them, painted over to look “normal” at a distance, complete with fake windows and tires.

ISIS has also been reportedly mounting explosively-formed penetrators and anti-tank mines to the front of the car bombs to direct the blast toward defending troops.

A lucky-to-be-alive AFP photographer captured a fireball from one, here.

(These pictures beg the question: Why does ISIS put so many car bombs in Kias? Possibly because they took over a Kia dealership when they moved into Mosul back in 2014.)

To stymie the Iraqi offensive, ISIS has also been barricading the street with looted cars and garbage, as this photo shows.

On the coalition side, HIMARS artillery has been pounding ISIS positions in west Mosul. Video footage, here.

The coalition may also be dealing with some bad news this morning: “At least 33 former members of Iraqi security forces were killed in a U.S.-led coalition raid in western Mosul on Monday, according to a local police officer,” Turkey’s Anadolu news agency reports this morning. “Federal police officer Abdullah al-Mayahi said Daesh militants had held dozens of former members of the security forces to question them about an alleged collaboration with the Iraqi army. He said a coalition warplane mistakenly fired two missiles into a train station, where the captives were held...According to al-Mayahi, a number of Daesh militants were killed and injured in the airstrikes.” More here. There’s more from the Syrian side of the ISIS fight below.

From Defense One

USAF Wants to Test a Laser on an Attack Plane Within A Year // Marcus Weisgerber: But the U.S. Special Operations Command still needs money for the test and policymakers need to figure out the rules of engagement.

Chinese Military Officers Crash US Airpower Conference // Marcus Weisgerber: The three officers, armed with cameras, took a stroll around an exhibit hall of new weapons and technology.

Russia Has Deployed a Treaty-Violating Missile. Here's What the US Should Do About It // Stimson Center founder Michael Krepon: Hint: it's not what we would have done in the 1950s, '60s, '70s, or '80s.

A US-Based Army Can't Get to the Fight Fast Enough // AUSA’s Carter Ham: We need to rebuild our forward-based troop strength, get serious about strategic lift, and more.

America Is Facing a Dangerous Enemy. We Just Can't Agree Who It Is // The Atlantic’s Uri Friedman: Our ideological adversary is powerful, authoritarian, and spreading. And it is completely different depending on which government officials you're talking to.

Killing Free Trade Will Rob the World of a Highly Effective Deterrent to War // Dan Kopf, via Quartz: Trade agreements are rarely about economics alone.

The Government's Intelligence Wiki Might Be a Lockbox for Russian-Hacking Secrets // The Atlantic’s Kaveh Waddell: Analysts reportedly tucked classified information about Russian election meddling inside Intellipedia for safekeeping.

Welcome to this Monday edition of The D Brief by Ben Watson and Bradley Peniston. #OTD1945: Nazi Germany launches its last offensive, in Hungary. (Got a tip? Let us know by clicking this link to email us: the-d-brief@defenseone.com.)

Trying to wrap your head around President Donald Trump’s evidence-free wiretapping accusations? So is Lawfare’s Ben Wittes. Taking stock of reporting by NYT and an attempt to sort out what we know by Cato Institute’s Julian Sanchez, the Brookings scholar poses “10 More Questions for President Trump.”

Meanwhile, Washington lawyer Stewart A. Baker, who served as DHS’ first policy chief and earlier as general counsel for the NSA, offers “Eight Buckets of Cold Water for The Trump Wiretap Story.”

And Third Way’s Mieke Eoyang connects Trump’s tweets to the ongoing inquiries into his campaign’s contacts with Moscow: “We don’t know who’s wiretapping whom. That’s why Americans need to get the truth about the president’s ties to Russia, and soon.” Read, here.

Speaking of taking stock: here are the most recent attempts by WaPo and NYT to wrap up what’s known and unknown about the connections between the Trump campaign and Russia.

Coming this week: Trump is expected to order the dismantling of restrictions on automobile emissions and other Obama administration efforts to slow the release of greenhouse gases. Via NYT, here. (ICYMI: The U.S. military is already struggling to adapt to climate change’s effects on its installations and global security. National Geographic took a detailed look last month.)

The Pentagon’s plan to retake Raqqa from ISIS could involve “increased Special Operations forces, attack helicopters and artillery, and arms supplies to the main Syrian Kurdish and Arab fighting force on the ground,” the Washington Post reported this weekend, calling these “[t]he military’s favored option among several variations currently under White House review.”

The need-to-knows: “Rather than a wholesale revision, the new proposal calls for increased U.S. participation, with more personnel and equipment and less-restrictive rules. As they have in support of the Iraqi military in Mosul, U.S. fixed-wing aircraft and attack helicopters would actively back the ground force. U.S. owned and operated artillery would be moved into Syria to pound the militants from afar, while more Special Operations troops would move closer to the front lines — requiring more U.S. military assets to protect them. The SDF — both Kurds and Arabs — would be supplied with weaponry along with vehicles and equipment to travel through and disarm what are expected to be extensive minefields and other improvised explosive devices along the way.”

Worth noting: “Approval of the Raqqa plan would effectively shut the door on Turkey’s demands that Syrian Kurds, considered terrorists by Ankara, be denied U.S. equipment and kept out of the upcoming offensive.”

And this point has become particularly important in recent days, the Post writes, since “photographs posted on social media showed U.S. military vehicles headed into Manbij from the east” while “the U.S. military confirmed that it had ‘increased force presence in and around Manbij to deter hostile acts, enhance governance and ensure there’s no persistent YPG presence,’ effectively inserting U.S. forces to keep two coalition members — Turkey and the Syrian Kurds — from fighting.” Read the rest, here.

U.S.-backed Syrian fighters have cut the main road connecting ISIS-held Raqqa from Deir ez-Zour, Syria, multiple agencies report this morning. “The Britain-based Syrian Observatory for Human Rights said SDF fighters cut the road linking the two cities in the area of Jazra near Raqqa early Monday,” AP reports. “The group said it is now difficult for people to leave and enter Raqqa with the new territory captured east of the city and after last month's airstrikes by the coalition that destroyed two main bridges on the southern edge of Raqqa.”

Reuters: "Cutting the road between Raqqa and Deir al-Zor means that practically the encirclement of the Daesh (Islamic State) capital is complete by land," a Kurdish military source told Reuters, adding that the only remaining way out of the city was south across the Euphrates River.

The SDF re-launched their offensive after taking a one-week break, Voice of America reports. “Their strategy includes isolating the city from Deir Ezzor in eastern Syria, and to take control of more territories along the Euphrates river en route to Raqqa.”

Simultaneously, the Syrian army is also advancing east from Aleppo city towards the Euphrates, Reuters reports. The stated goal there: seize a water station in a village called al-Khafsa—while possibly also having the additional “effect of deterring further advances south by Turkish forces and their Free Syrian Army (FSA) rebels as they carve out an effective buffer zone near the border in areas seized from Islamic State.” More from Reuters here.

Elsewhere in the region: A 56-year-old Syrian pilot is reportedly in a Turkish hospital after his jet crashed early Sunday “in the Antakya area of Turkey’s Hatay province, 35 kilometres from the Syrian border,” Rudaw news reported. Rebel group Ahrar al-Sham claimed to have shot down the Syrian jet in Idlib province, near Turkey’s border. “Syrian military sources confirmed to state-run SANA news that they had lost contact with one of their planes carrying out a reconnaissance mission near the Turkish border,” Rudaw reports—adding somewhat curiously at the end: “The cause of the crash is unknown at present but Turkish officials said there were no concerns of border violations.” More here.

The U.S. is also reportedly expanding its runway operations in Kobani, Syria, an SDF “source” told Kurdish Bas News this morning. “The source explained that ‘the airport runway in the past was 1,100 meters long with the width of 60 meters, and it is expected to be expanded to 1,700 meters long and 110 meters wide,’ adding that a four-meter-tall wall will also be erected around the airport…

ICYMI: “The US troops currently possess two military bases in the Kurdish areas of Kobani and Rmelan in northern Syria for logistical purposes in support of the SDF in the battle against the Islamic State in Syria.” More here.

The drone war in Yemen is heating up. "Suspected U.S. drones fired missiles at al Qaeda targets in two separate attacks in Yemen on Monday," Reuters reports. The locations included "the home of an al Qaeda suspect in the village of Noufan in central al-Bayda province, and another struck a mountainous area believed to house a training camp in al-Saeed in southern Shabwa province."

More Yemen airstrike math, this time from Fox News’ Lucas Tomlinson: “US military averaged 30 airstrikes per year in past 5 years against AQAP in Yemen. Already exceeded that average in first months of 2017.”