Secretary of State John Kerry spoke with his Russian Foreign Minister Sergei Lavrov, by phone Tuesday — as the European Union set a deadline to preparing more responses against Moscow's occupation of Ukraine's Crimea region.
The Kerry-Lavrov call came after Russia responded to list of questions posed by the United States over the weekend to assess Moscow’s support for a de-escalation of the crisis. The U.S. called the response insufficient and said the environment for diplomacy was not there yet.
"They have not taken de-escalatory steps. However, I would not say it's as black and white in our view," State Department spokeswoman Jen Psaki said Tuesday, noting that Kerry and Lavrov are continuing their discussions.
The dialogue comes ahead of Ukrainian Prime Minister Arseniy Yatsenyuk visit to the White House on Wednesday, where he and President Barack Obama are expected to discuss a peaceful resolution to Russia's military intervention in Crimea.
The visit is also meant to highlight U.S. support for the people of Ukraine, the White House said.
In the face of Western moves, Russian forces continued to tighten their grip on the Crimean peninsula in Ukraine and have refused to back down in the face of international pressure.
Crimea has scheduled a referendum for Sunday on whether to secede and join Russia, a vote the new government in Kiev and its Western backers have denounced as illegal.
Meanwhile, European leaders said they would prepare more measures absent Russian movement on the Ukraine question by the weekend.
That deadline was issued by Germany's foreign minister in a warning echoed by the Polish prime minister.
"If the weekend passes without a visible change in Russia's conduct then on Monday in the European (foreign affairs) council we will have to discuss a next stage of measures," German Foreign Minister Frank-Walter Steinmeier said during a visit to the Estonian capital Tallinn.
"We don't want confrontation but the action of the Russian side unfortunately makes it necessary for us to prepare, as I have just outlined to you," he said on a one-day swing through the three Baltic states, all former Soviet republics and now NATO and EU members.
Speaking in Warsaw, Polish Prime Minister Donald Tusk told reporters: "When it comes to sanctions on Russia, a decision has in fact already been made, especially on the procedure of introducing sanctions. The consequence of this will be the start of sanctions on Monday."
Poland has taken a hard in the Ukraine crisis against Russia, its former overseer. Also, Poland and Ukraine share a border and large sections of the Ukraine were Polish before World War II.
Sources have told NBC News that the U.S. is working closely with its Western allies on new sanctions against Moscow if the Russian assembly, the Duma, approves annexation of Crimea.
In another move, the European Commission agreed give nearly 500 million euros ($685 million) worth of trade benefits to Ukraine, which had been teetering towards default even before pro-Western unrest in Kiev stoked East-West tensions. The United States has pledged $1 billion in financial assistance to Ukraine.
Andrea Mitchell of NBC News and Reuters contributed to this report.