Will the US officially declare war on Iran by December 31, 2026?

Prediction markets put the probability at 6%: Will the US officially declare war on Iran by December 31, 2026. Currently, markets see this as unlikely (6% YES). US declaration of war on Iran.

What’s Happening

The question of whether the US officially declare war on Iran gained renewed urgency after CENTCOM confirmed an escalation of military operations following the collapse of a fragile ceasefire. According to reporting, the U.S. launched its largest bombing wave since the ceasefire broke down, striking numerous Iranian targets after Iran resumed attacks on commercial vessels in the Strait of Hormuz. Retired U.S. Air Force officer Karen Kwiatkowski flagged the logistical strain facing American forces sustaining strikes at this tempo. The current campaign traces back to Operation Epic Fury, the joint U.S.-Israel initiative launched earlier in 2026 that followed the death of Iran's Supreme Leader, Ayatollah Ali Khamenei. [Crypto Briefing, Jul 13]

Hawkish voices point to President Donald Trump's warning on July 8 that the U.S. was preparing "another night of strikes," delivered hours after he declared the ceasefire over while insisting negotiations could continue. Iran's Islamic Revolutionary Guard Corps (IRGC) exchanged fire with U.S. forces over the Strait of Hormuz and vowed to persist with attacks until perceived U.S. interference ends. Analysts caution, however, that sustained airstrikes and naval clashes do not equate to a formal declaration — a distinction that matters for whether the US officially declare war on Iran in a legal sense. UN Secretary-General António Guterres urged an immediate halt, warning of catastrophic consequences for the region and global economy. [AP, Jul 9]

The structural factor determining resolution is procedural: modern U.S. administrations have consistently conducted hostilities under executive authority rather than seeking a congressional declaration of war — the last such declaration was in 1942. Despite active combat, no move toward a formal vote has emerged, and Trump has kept a diplomatic channel open. For the us officially declare war on Iran before December 31, 2026, Congress would need to pass a formal declaration, an outcome that remains historically rare even amid open conflict. [Crypto Briefing, Jul 12]

Traded on Polymarket — $646K Volume

Polymarket prices this at 6c YES with $646K in volume. Moderate liquidity — use limit orders for positions above $1K to avoid moving the price.