Ukrainians on Twitter are deriding claims that a far-right leader's business card was found at the site of an attack on a checkpoint manned by pro-Russian activists. Sunday's gun battle, which occurred near the eastern Ukrainian city of Slovyansk, left three dead and a fragile truce on the brink of collapse.

Even as the crisis inUkraine continues to defy easy resolution, President Obama and his national security team are looking beyond the immediate conflict to forge a new long-term approach to Russiathat applies an updated version of the Cold War strategy of containment.

Poland’s foreign minister, Radoslaw “Radek” Sikorski, has been intimately involved in the Ukraine crisis, including in the negotiation of an agreement in February that then-Ukrainian President Viktor Yanukovych walked away from, further fueling the Maidan protest.

From Kiev to Damascus, Moscow to Caracas, there are very few international conflicts and debates where the actions and position of the United States is not influential. In Ukraine, the United States stands solidly behind the interim government, and slapped some sanctions on Russian officials after Moscow annexed Crimea.

The United States plans to carry out small ground-force exercises in Poland and Estonia in an attempt to reassure NATO’s Eastern European members worried aboutRussia’s military operations in and nearUkraine, Western officials said Friday.

The United States, Russia, Ukraine and the European Union reached an agreement here on Thursday evening that calls for armed pro-Russian bands to give up the government buildings they have seized in eastern Ukraine and outlines other steps to de-escalate the crisis.

Russian President Vladimir Putin has warned Ukraine is "on the verge of civil war." The Kremlin said Putin made the comment in a telephone call with German Chancellor Angela Merkel on the situation there.