Schlumberger, the world’s largest oilfield contractor, has $400 million in unpaid bills stranded in Russia as the country’s international isolation deepens.

The carrying value of Schlumberger’s net assets in Russia is about $1 billion, according to a federal filing. The receivables figure was as of June 30.

Schlumberger hasn’t gone as far as rivals Baker Hughes Co. and Halliburton Co. in disengaging from Russia more than four months after Vladimir Putin’s invasion of Ukraine triggered international outrage. Chief Executive Officer Olivier Le Peuch has said the company’s unique corporate structure gives it flexibility to work in Russia while fully complying with US and EU sanctions.