MOSCOW (Reuters) - Russia's largest lender Sberbank said on Thursday that all of its systems were working normally and that it was prepared for any developments after Russian forces attacked Ukraine, a move that could trigger sanctions on the bank.

Russian forces fired missiles at several cities in Ukraine and landed troops on its coast on Thursday, officials and media said, after President Vladimir Putin authorised what he called a special military operation in the east.

A senior U.S. administration official told reporters on Tuesday that Sberbank and No. 2 lender VTB would face U.S. sanctions if Moscow proceeded with its invasion of Ukraine, warning that no Russian financial institutions were safe.

"We are prepared for any development of the situation and have worked through scenarios for guaranteeing that our customers funds, assets and interests are protected, and also that our functions are fully operational," Sberbank said on Thursday.

The bank has previously declined to comment on potential sanctions threats.

The Moscow Exchange suspended trading on Thursday shortly after the rouble plunged to its lowest since early 2016.