Russia’s dollar-denominated sovereign bonds tumbled on Thursday after U.S. Defense Secretary Jim Mattis said Moscow must be held accountable for its attempts to hack the Organization for the Prohibition of Chemical Weapons (OPCW).

The 2047 issue fell 2.2 cents to trade at 93.348 cents, its steepest daily loss since April, according to Tradeweb data.

Earlier, Britain and the Netherlands accused Russia of running a global campaign of cyber attacks to undermine Western democracies, including what the Dutch government described as an attempt to hack into the U.N. chemical weapons watchdog.

Russia has denied the accusation