SEOUL, South Korea (AP) — President Barack Obama says the United States and European leaders are laying the groundwork for sanctions against sectors of Russia's economy if Moscow launches a military incursion into Ukraine.

He says he'll call key European leaders this evening to discuss what's happened since a deal was reached last week to de-escalate the crisis.

Obama is offering the clearest indication to date of what criteria the U.S. will use to decide what costs to impose on Russia.

He's suggesting it would require a Russian military incursion into eastern Ukraine to trigger so-called sectoral sanctions against broad parts of Russia's economy, such as the energy sector. So far, the U.S. has slapped sanctions on individuals but hasn't targeted economic sectors.

Obama spoke in South Korea during a trip to Asia.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.