The 10th Special Forces Group encountered a unique problem in frigid Alaska. Jumping from a warm aircraft into subzero temperatures wreaked havoc on their parachute systems and electronics. They eventually found a counterintuitive solution: Use only individual gear to stay warm by wearing heated gloves and masks. This method would chill the aircraft and their gear as they ascended, creating a gradual cooling effect that would allow the equipment to remain cold and effective after jumping.

That’s one of the firsthand accounts Mr. Seward brought back from his time embedded with elite Army units in the Arctic, where U.S. troops are training for combat in one of the planet’s most brutal, inhospitable environments. 

His exclusive reporting from the region underscores just how vital the Arctic region is now viewed in the context of 21st-century great power competition. America’s most elite military units are tasked with preparing for potential combat in the extreme conditions of the far North.

It’s emerged as perhaps the most critical battlespace in the U.S.-Iran war: The narrow Strait of Hormuz, through which at least 20% of the world’s oil supply travels.

At least 18 commercial ships have been attacked while traveling through the strait since the war began nearly two weeks ago. New Iranian Supreme Leader Ayatollah Mojtaba Khamenei said his country should use the closure of the waterway as leverage. 

Although much of Iran’s conventional navy has been eliminated, American and Israeli forces might still struggle to clear the strait and maintain full control over it. Iran’s arsenal of thousands of sea mines and hundreds of speedboats, underwater attack drones and unmanned surface vessels has allowed Tehran to bring maritime traffic in the strait to a near-total halt.

There has been clear economic fallout. Oil prices have soared since the war started, rising from $70 a barrel of Brent crude, the international standard, to more than $100 a barrel. That’s mostly because of the panic over potential oil shortages and the growing realization that fully reopening the strait could take weeks or even months.

National Security Correspondent Bill Gertz zeroed in on this key finding from a recent military think tank report: China’s rapidly expanding arsenal of nuclear warheads is stored at mountain facilities that are vulnerable to strikes or disruption.

Mr. Gertz explains how the information sheds new light on one of China’s most important strategic secrets. The report from the Air Force’s China Aerospace Studies Institute details how the Chinese military stores, tests, guards and transports strategic and tactical warheads from a central facility in the Qinling Mountains, some 1,200 miles southwest of Beijing.

It’s a rare window into how the Pentagon assesses the Chinese system for storing and handling nuclear weapons. And it highlights valuable information for U.S. war planners who would be charged with conducting preemptive strikes on those nuclear warhead facilities.

The two events on opposite sides of the world came within hours of one another. In Seoul, lawmakers approved a massive $350 billion investment of South Korean money in U.S. shipbuilding and other strategic industries.

Around the same time, the Trump administration announced that it was initiating Section 301 investigations against 16 nations, including South Korea. The powerful Section 301 of the U.S. Trade Act grants authority to investigate alleged unfair trade practices and apply tariffs to guilty parties.

Asia Editor Andrew Salmon makes sense of both developments and their potential impact on the strategically vital U.S.-South Korean alliance. 

America’s war on terror groups abroad has now lasted almost 25 years. Yet presidents of both parties have neglected for years to take real military action against the epicenter of Islamic extremism: The Islamic republic of Iran.

In a new piece, national security and foreign affairs columnist Jed Babbin explains in The Washington Times why he believes Mr. Trump should seize the moment and finally deal with the root of the problem. Iran is widely considered the world’s No. 1 state sponsor of terrorism. It backs Lebanon-based Hezbollah, Gaza Strip-based Hamas, the Houthi rebels of Yemen, dangerous Shiite militias in Iraq and Syria, and other terror outfits.

“We have to face the fact that a nuclear-armed Iran is a danger to us, our NATO allies and Israel. Iran, as has too often been stated, is the principal supporter of terrorism around the globe. It must be a fight to the finish of Iran’s terrorist regime. Iran knows this, and it will fight as long as it can,” Mr. Babbin writes. “It’s up to President Trump to finish the job, which means regime change in Iran.”

• March 17 — Boosting U.S. Quantum Supply Chains for Enduring Advantage, Center for a New American Security 

• March 18 — Implementing a U.S. Cyber Force: A Conversation with Rep. Pat Fallon, Texas Republican, Center for Strategic and International Studies

• March 19 — Ukraine on the Mental Map of Europe, Brookings Institution 

• March 19 — Poland, Northeastern Europe and the Future of the Transatlantic Partnership, American Enterprise Institute

• March 20 — The Fight for Influence in Venezuela Against Russia, China, Iran and Cuba, Atlantic Council

• March 24-26 — Global Force Symposium & Exposition, Association of the U.S. Army