U.S. officials spent hundreds of hours over five months debating, crafting and then touting a punishing array of economic sanctions to try to scare Russian President Vladimir Putin off invading Ukraine, but almost from the beginning, many shared the same view: This strategy probably won’t work.

Those concerns became reality Thursday after Putin announced a military operation to "protect” the Donbas region of Ukraine, raising fears of an imminent, full-scale invasion across the entire country. In a late-night statement, U.S. President Joe Biden said that he would announce "further consequences” for Russia later Thursday, in addition to sanctions unveiled earlier in the week.

Biden on Tuesday had set out a partial "first tranche” of sanctions — a modest package that underwhelmed political observers and financial markets — then followed up with additional measures the following day, including sanctions against Nord Stream 2 AG, the company that built the $11 billion natural gas pipeline connecting Russia and Germany. Biden’s aides have said they’re holding heavier punishments in store — but behind the scenes, there’s persistent skepticism about the strategy.