British Prime Minister Keir Starmer authorized the armed forces to board and detain ships from Russia's shadow fleet in UK waters yesterday, escalating efforts to curb Moscow's sanctions evasion.

Defence Secretary John Healey told BBC Radio 4's Today programme this morning that forces are now "ready to act" after completing training and securing a legal basis. The authorization allows military and law enforcement personnel to intercept sanctioned vessels, even if crews are armed or attempt evasion, with potential criminal proceedings against owners and operators.

Russia's shadow fleet comprises ageing tankers with opaque ownership that transport about 75% of its crude oil exports, generating revenues to fund the war in Ukraine. The UK has sanctioned 544 such vessels, many of which pass through the English Channel. Dozens have been tracked in UK waters since January, when ministers identified a legal pathway under the Sanctions and Money Laundering Act 2018.

Starmer, speaking ahead of the Joint Expeditionary Force summit in Helsinki today, said the measures would starve "Putin's war machine of the dirty profits that fund his barbaric campaign in Ukraine." Healey added that operations were "lined up and ready," sending a "signal to Putin" amid distractions from the Middle East conflict.

Special Boat Service and Royal Marines have trained for high-risk scenarios, including standoffs with armed personnel. Planners are monitoring tracking systems for the first target, with recent joint operations alongside Finland, Sweden, and Estonia.

Ukrainian President Volodymyr Zelensky welcomed the decision on X, calling it a "timely move" to cut Russia's illegal oil revenues, which directly finance the invasion. "Sanctioned tankers must be stopped, their oil seized," he wrote. The move follows UK support for a US seizure of a shadow fleet tanker in January and aligns with European actions, such as France diverting a suspect vessel.

Russia has warned of countermeasures, with a senior official claiming the navy would protect against "western piracy." No boardings have occurred yet, but officials expect action soon as part of broader pressure at the Helsinki summit.

The shadow fleet poses environmental risks from poorly maintained tankers prone to spills. Starmer emphasized defending UK sovereignty while standing with Ukraine "for as long as it takes." Conservatives supported the effort but criticized Labour's defence spending.