There will be few days that better symbolize the crisis in Ukraine.

On Friday:

As Ukrainian Prime Minister Arseniy Yatsenyuk was signing an agreement on closer relations with the European Union ...... Russian President Vladimir Putin was signing the laws his country has put in place to take Crimea from Ukraine and make it part of the Russian Federation.

Ukraine's pact with the EU, as CNN notes, has "symbolic force because it was the decision of ousted Ukrainian President Viktor Yanukovych in November to ditch it in favor of closer ties with Russia that triggered the protests that spiraled into the current crisis."

The BBC says that "the EU Association Agreement is designed to give Ukraine's interim leadership under PM Arseniy Yatsenyuk economic and political support. EU President Herman Van Rompuy said in a statement that the accord 'recognises the aspirations of the people of Ukraine to live in a country governed by values, by democracy and the rule of law.' "

But, as CNN adds, "Russia's moves to annex Crimea, following a contested weekend referendum in the Black Sea peninsula, have turned a confrontation with Europe and the United States into the biggest crisis in East-West relations since the Cold War." The U.S. and EU nations say the annexation violates both international and Ukrainian law.

Meanwhile, NPR's Ari Shapiro reports from London that the EU has added 12 names to its list of Russian and Ukrainian officials who it says were involved in interfering in Ukraine's affairs. Those officials are now subject to "visa restrictions and asset freezes," Ari says. Twenty-one officials were put on the EU's list earlier this week.

On Thursday, President Obama announced that the U.S. had increased the number of Russians and Ukrainians on its sanctions list to 31. The Russian government responded by barring nine Americans — including six members of Congress — from traveling to Russia. Putin has spoken about taking more steps.

Ukraine has said it will withdraw its troops and sailors from Crimea. Russian forces, along with local "self-defense" units, have taken control of many bases there and other strategic locations. On Friday, the BBC reports, families of Ukrainian military personnel in Crimea were seen departing from bases.

Also Friday, U.N. Secretary-General Ban Ki-moon arrived in Kiev. Ban, who is trying to find a diplomatic solution to the crisis, was in Moscow on Thursday. "I have emphasized that all parties (should) refrain from any hasty or provocative actions that could further exacerbate the already very tense and very volatile situation," he said after meeting with Putin.

Background

As the crisis in Ukraine has developed over recent weeks, we've tracked developments. Here's a recap:

Crimea has been the focus of attention as the ripple effects of the protests that led to last month's ouster of Yanukovych have spread.Summing up the history and importance of Crimea to Russia and Ukraine isn't possible in just a few sentences, of course. The Parallels blog, though, has published several posts that contain considerable context:-- Crimea: 3 Things To Know About Ukraine's Latest Hot Spot-- Crimea: A Gift To Ukraine Becomes A Political Flash Point-- Why Ukraine Is Such A Big Deal For RussiaShortly after Yanukovych was deposed and fled Ukraine, Russia moved to take control of Crimea by sending thousands of troops there to secure strategic locations. Along with "local defense forces," those soldiers surrounded Ukrainian military facilities.This week, after Crimeans voted to join the Russian Federation, Russian President Vladimir Putin signed a treaty to annex the region. The U.S. and European Union have objected, calling that action a violation of international law. Putin says he is supporting Crimeans' right to "self-determination."We've recapped what set off months of protest in Kiev and ultimately led to Yanukovych's dismissal by his nation's parliament last month this way:"The protests were sparked in part by the president's rejection of a pending trade treaty with the European Union and his embrace of more aid from Russia. Protesters were also drawn into the streets to demonstrate against government corruption."It was after Yanukovych left Kiev and headed for the Russian border that troops moved to take control of strategic locations in Crimea.Copyright 2016 NPR. To see more, visit http://www.npr.org/.