EXPLAINER: A look at West's toughest sanctions yet on Russia

WASHINGTON (AP) — The United States joined European allies Saturday in dramatically escalating financial penalties against Russia over its invasion of Ukraine, after the West’s initial rounds of sanctions failed to deter Russian President Vladimir Putin in his military offensive.

Two of the key new measures target the heart of Russia's financial system, its Central Bank, and cut an unspecified number of Russia's banks off from the SWIFT financial network. SWIFT is a vital element of global commerce and banking that moves money from bank to bank around the world.

U.S. and European officials made clear they still were working on implementation of the sanctions, and said they would take care not to impact European purchases of Russian natural gas.

U.S. officials said the moves would send Russia's ruble currency crashing in value, and intensify its isolation financially. It's the latest and toughest in days of new sanctions since Russian forces moved into Ukraine late last week.

A look at Saturday's measures and earlier ones. In all, they potentially amount to some of the toughest sanctions imposed on any nation in modern times.

HITTING AT RUSSIA'S CENTRAL BANK

The new restrictions that the United States, European Union and United Kingdom announced for Russia's Central Bank would limit the Kremlin's ability to access the more than $600 billion in reserves there. If the West is able to implement the Central Bank restrictions as it aims to, it will cripple Russia’s ability to keep the ruble from crashing in value amid the tightening Western sanctions.

The likely result, U.S. officials told reporters Saturday: The Russian ruble goes into free fall, triggering spiraling inflation there.

Specifically, by limiting Russia’s ability to sell off its international reserves, the...