Copper fell the most in more than four months as tensions in Ukraine escalated and European nations threatened further economic sanctions against Russia.

Ukrainian President Petro Poroshenko Thursday called an emergency meeting to defend against what he called a “de facto” Russian incursion after separatists gained ground in intensified fighting. Warnings by France and Germany that they may expand measures against President Vladimir Putin dimmed Russia’s growth outlook, fueling concern that demand for metals will slow.

The rise in tension “was enough to shake the markets quite a bit,” Daniel Briesemann, a commodities analyst at Commerzbank AG, said in a telephone interview from Frankfurt. “Overall, we have some risk-off moves.”

Copper futures for December delivery dropped 1.5 percent to settle at $3.1505 a pound at 1:12 p.m. on the Comex in New York, the biggest decline since April 15.

The chance of Russia’s economy tipping into a recession is rising as the crisis raises the risk of the government in Moscow retaliating with further import bans, according to a survey of analysts.

On the London Metal Exchange, copper for delivery in three months lost 1.4 percent at $6,934 a metric ton ($3.15 a pound).

Aluminum for delivery in three months on the LME slid 0.2 percent to $2,081 a ton. Nickel, lead and zinc declined, while tin advanced.