Kiev, Ukraine (CNN) -- Western powers increased pressure on Russia Wednesday to talk to the new government in Kiev in a bid to ease tensions over Russia's military intervention in Ukraine's Crimea region.
Russia has been warned that possible sanctions will be on the agenda when European Union leaders meet Thursday in Brussels, Belgium, if no progress is made in ending the high-stakes showdown.
But such measures may not only hurt Russia. In a tit-for-tat move, Russian lawmakers are drafting a law that would allow Russia to confiscate assets belonging to U.S. and European companies if sanctions are slapped on Moscow, Russian state media reported.
The diplomatic maneuvers come as world leaders meet in Paris for talks that were intended to focus on Lebanon. Instead, Ukraine will likely dominate the agenda.
Russian forces remain in effective control of Crimea, a Black Sea peninsula where Russia has a large naval base, in a tense standoff with Ukrainian forces loyal to the new interim government in Kiev.
U.S. Secretary of State John Kerry and his Russian counterpart, Sergey Lavrov, are due to hold crucial bilateral talks later in the day.
Meanwhile, a "brief and informal discussion" has already taken place on the sidelines of the meeting between Kerry, Lavrov, Britain's William Hague, France's Laurent Fabius and German Foreign Minister Frank-Walter Steinmeier, a senior State Department official said.
But Hague said what happens at the EU meeting on sanctions "will be partly determined by Russia's willingness to sit down with Ukraine."
If no progress can be made on de-escalating the situation, then there will be "costs and consequences," Hague said.
"It will be a test this afternoon of whether Russia is prepared to sit down with Ukraine. And we will strongly recommend that they do so."
Kerry: Clear legal obligations at stake
Hague's comments came after he, Kerry and Ukrainian Foreign Minister Andrii Deshchytsia discussed their next steps ahead of Lavrov's arrival in the French capital.
Kerry reminded Moscow that it had, like Washington and London, signed an agreement in 1994 when Ukraine agreed to give up nuclear weapons "to refrain from the threat or use of force against the territorial integrity or political independence of Ukraine."
There are "very clear legal obligations that are at risk in this," Kerry said.
Deshchytsia said he hoped for bilateral and multilateral consultations with Russia.
At issue is Russia's insistence that the new government in Ukraine is not legitimate, which means it does not recognize its authority.
Western powers argue in return that ousted President Viktor Yanukovych fled the country, leaving a void that had to be filled. The interim government was voted in with a large majority in parliament, including by members of Yanukovych's Party of Regions, they point out.
In a joint statement after their meeting, the United States, the United Kingdom and Ukraine called for international observers to be deployed to Ukraine.
This, they said, "would help address any concerns regarding irregular forces, military activity and the treatment of all Ukrainians irrespective of their ethnicity or spoken language."
Russia has cited a threat to ethnic Russians in Ukraine as a justification for military intervention in the country.
Lavrov said earlier Wednesday that decisions on whether international observers should be sent into Ukraine are for leaders in the country to make.
The Organization for Security and Co-Operation in Europe, a regional security bloc, said Wednesday it was sending 35 unarmed military personnel to Ukraine in response to a request from Kiev.