UKRAINE CONFIRMS COUNTEROFFENSIVE NORTH OF LYMAN
Ukraine's 3rd Army Corps commander confirmed on September 15 that Ukrainian forces are conducting Operation Vivaldi, a counteroffensive against the Russian salient northwest of Lyman, clearing 85 square kilometers. ISW assesses these gains have disrupted Russia's plan to encircle Ukraine's Fortress Belt from the north and south.
AT A GLANCE
NEW | UKRAINE | Ukrainian officials confirmed counteroffensive gains northwest of Lyman while Zelensky repeated an offer for a mutual energy ceasefire.
CARRIED FORWARD, SEP 11 | IRAN | Houthi forces reportedly seized Yemen's Red Sea coast, Perim Island, and Dhubab, positioning near the Bab al Mandeb Strait.
CARRIED FORWARD, SEP 11 | TAIWAN | Taiwan's Executive Yuan proposed a supplementary defense budget while PRC coast guard ships continued patrols east of Taiwan.
CARRIED FORWARD, SEP 9 | KOREA | North Korea revised its party charter and commissioned the destroyer Kang Kon, prioritizing its East Sea Fleet.
WHY THE LYMAN COUNTEROFFENSIVE MATTERS
Ukraine's 3rd Army Corps commander publicly confirmed for the first time that Ukrainian forces are conducting a deliberate counteroffensive, Operation Vivaldi, rather than only defensive holding actions northwest of Lyman. ISW notes Russian sources are beginning to acknowledge these losses.
The 3rd Army Corps paired ground gains with an intermediate-range strike campaign against Russian logistics up to 120 kilometers from the front, which reportedly forced Russia to shut a fuel pipeline into occupied Luhansk Oblast and relocate support units.
ISW assesses these gains have rendered Russia's plan to encircle Ukraine's Fortress Belt from the north and south unfeasible, and a Kremlin-affiliated milblogger reportedly agreed that the advances will delay Russia's planned push on Sloviansk.
Separately, Zelensky again offered a mutual ceasefire on energy infrastructure, contingent on US assurance that Russia is genuinely prepared to stop the war. Kremlin spokesperson Peskov called the proposal a good idea but deflected, citing sanctions relief as a prerequisite.
OTHER SIGNALS
IRAN | HOUTHIS REPORTEDLY EXPAND NEAR BAB AL MANDEB
ISW report of September 11 · carried forward
ISW's September 11 Iran Update reports the Houthis have expanded control along Yemen's Red Sea coast, reportedly seizing the Greater and Lesser Hanish islands, Dhubab, and Perim Island in the Bab al Mandeb Strait, according to Yemeni government officials cited by international media.
ISW assesses these positions could let the Houthis threaten shipping with artillery or tactical drones if they choose to, though Houthi officials have publicly said they intend to maintain safe shipping. A Saudi pipeline was reportedly struck by drones launched from Iraq on September 10.
TAIWAN | BUDGET AND MISSILE MOVES DRAW PRC PRESSURE
ISW report of September 11 · carried forward
ISW's September 11 China and Taiwan Update reports Taiwan's Executive Yuan proposed a supplementary defense budget of roughly 4.6 billion dollars for uncrewed systems, missile programs, and ammunition stocks, now awaiting Legislative Yuan review, alongside a newly revealed Ching Tien series long-range cruise missile.
ISW assesses the missiles could improve Taiwan's ability to retaliate against PRC strikes and support a base-denial campaign. Separately, Chinese coast guard ships continued month-long patrols east of Taiwan, which ISW assesses may be normalizing a permanent PRC maritime presence there.
DEFENSEHUB ASSESSMENT
MEDIUM CONFIDENCE: Ukrainian gains northwest of Lyman and Russian acknowledgment of losses strengthen the case Russia's encirclement plan has stalled, while continued Kremlin deflection on the ceasefire weakens near-term de-escalation prospects.
CALL, 30 DAYS: Ukraine's Operation Vivaldi will likely report further territorial gains northwest of Lyman within 30 days. Falsified by ISW reporting Russian forces recapturing Serednie, Kolodyazi, or Novoselivka within that period.
TRACK RECORD
TAIWAN · OPEN: Taiwan's Executive Yuan proposed a supplementary budget on September 11, but ISW reporting does not yet show Legislative Yuan review advancing.
KOREA · RETIRED: Kang Kon's commissioning and Kim's East Sea remarks have been repeated across three issues without new movement in the supplied snapshots.
72-HOUR OUTLOOK
UKRAINE: Watch for further Ukrainian 3rd Army Corps statements detailing additional Operation Vivaldi gains or Russian counterattacks near Kolodyazi.
IRAN: Watch whether Houthi forces use new Bab al Mandeb positions to target commercial or Saudi shipping directly.
TAIWAN: Watch whether Taiwan's Legislative Yuan advances review of the new supplementary defense budget in coming days.
KOREA: Watch for further North Korean statements or naval activity reinforcing East Sea Fleet priority after Kang Kon's commissioning.
SOURCES & METHOD
Sources: Russian Offensive Campaign Assessment, September 15, 2026, Iran Update, September 11, 2026, China & Taiwan Update, September 11, 2026, Korean Peninsula Update, September 9, 2026. DefenseHub separates reported facts, disputed claims, and analytical judgments. Each theater carries the date of its last admitted ISW report, and a theater with no newer report for six days keeps its AT A GLANCE line without a section of its own. TRACK RECORD scores indicators published in earlier issues.
R. Planche · DefenseHub