Leaders of the Group of Seven agreed to ratchet up sanctions against Russia and announced the move Friday night, but the leaders stopped short of targeting key sectors of Russia's economy.

A senior U.S. administration official said the sanctions could come as early as Monday and each country would determine which targeted sanctions to impose.

“These sanctions will be coordinated and complementary, but not necessarily identical,” he said.

If Russia troops amassed at the Ukrainian border invade, more serious sectoral sanctions will follow, deputy national security adviser Ben Rhodes later told reporters traveling with the president.

Tensions between Washington and Moscow reached a new high Friday when the Kremlin reportedly broke off all high-level talks between Russians and U.S. officials. A State Department spokeswoman on Twitter late Friday tried to clarify the situation, saying the U.S. had not suspended its interactions with senior Russian leaders and has not been informed by Russian leaders that they had decided to halt all discussions.

The G-7 announcement came after a conference call President Obama conducted Friday with European leaders the day after Secretary of State John Kerry leveled what appeared to be a final warning to Russia that it could face additional costs if it didn't follow through on an agreement to de-escalate the crisis in eastern Ukraine.

Members of the G-7 include the U.S., the United Kingdom, France, Germany, Italy, Canada and Japan.

“Given the urgency of securing the opportunity for a successful and peaceful democratic vote next month in Ukraine's presidential elections, we have committed to act urgently to intensify targeted sanctions and measures to increase the costs of Russia's actions,” they said in a statement.

This latest round of sanctions won't target broad sectors of the Russian economy, although Obama has said the U.S. is preparing those additional sanctions. Rhodes, however, said taking that step would be a very serious move because it would have ripple effects throughout the global economy.

Earlier Friday Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee, called for the U.S. to impose sectoral sanctions on Russia to demonstrate international support for the Ukrainian people and help the government there “pull off a free, fair [presidential] election” set for May 11.