Axios

North Korea has successfully produced a miniaturized nuclear warhead that can fit inside its missiles, according to a confidential July assessment from the Defense Intelligence Agency, The Washington Post reports. The Japanese Ministry of Defense also believes North Korea has achieved miniaturization. It is unclear whether North Korea has tested the miniaturized weapon.

• Why it matters: That's a complex technological feat that sets Pyongyang on the path to being able to launch nuclear attacks. The U.S. assesses that North Korea is likely to have the capability to launch intercontinental ballistic missiles by next year, and the country is hitting nuclear milestones much more quickly than experts had believed possible.
• Get smart: The reason miniaturization is so key is because a missile's range depends on how heavy the nuclear warhead is. The lighter the warhead, the farther it can fly.
• Read more: Experts weigh in on how ready the U.S. is for an attack from North Korea

U.S. commanders are preparing American troops to confront the Russian military threat in Eastern Europe, including reintroducing Cold War-era tactics, the NYT reports.

The training shift for the U.S. Army includes working in smaller operating groups that are harder to target, using camouflage to avoid surveillance drones and rocket attacks, repainting battle tanks from desert-tan to dark green to match the terrain, and launching military exercises to learn and prepare for Russian tactics. Last month, 25,000 American and allied forces practiced tactics, including nighttime aerial assaults, across Hungary, Romania, and Bulgaria over 10 days.

North Korea will "under no circumstances" negotiate on its nuclear weapons and missile programs, according to a note that North Korean Foreign Minister Ri Yong Ho gave reporters on the sidelines of the ASEAN Regional Forum in Manila, per CNN. North Korean state media slammed as an "outrageous delusion" the efforts to sanction Pyongyang in the hopes of negotiating, WSJ reports, and vowed "thousands-fold" revenge against the U.S., per The Guardian.

In a significant step, China signed on to the new U.N. sanctions against North Korea. Ri said that was evidence the U.S. has sought to "internationalize" what is actually a dispute between the U.S. and North Korea.