BRUSSELS, Oct. 4 - U.S. Secretary of State John Kerry said Tuesday that Western alliances are willing to work with Russia to seek solutions to end the crisis in Ukraine, but will stand firm on principles based on freedom and international law.

Speaking in Belgium, Kerry said NATO "does not seek to weaken, to contain or to divide their nation or any other nation,” according to the Voice of America. He said the alliance and EU countries want to work with a Russia that is just as committed to solving common challenges.

Relations between Moscow and Western allied nations have been increasingly strained since Russia annexed Crimea from Ukraine in 2014 and has been supporting pro-Moscow separatists in eastern Ukraine.

The United States has imposed sanctions against Russia for violating the sovereignty of Ukraine and NATO has deployed forces near Russian borders.

Kerry spoke in Brussels at a transatlantic relations event hosted by the German Marshall Fund and the U.S. Mission to the European Union.

Ukraine's army and pro-Russian separatists both announced Saturday the pull back of their troops from a small eastern city as agreed in a demilitarization accord signed last month.

Ukrainian military spokesman Valentyn Shevchenko said both sides had moved their forces to several kilometers away from Zolote.

Negotiators for Kiev and the pro-Moscow rebels reached an agreement in Minsk in September to demilitarize three frontline areas in eastern Ukraine, withdrawing heavy arms and fighters from the towns of Stanytsya Luhanska as well as Zolote in the Luhansk region and Petrovske in the Donetsk region.

The retreat of troops has not yet taken place in the other two cities, according to the separatists.

Enacting this accord would create a security perimeter of two kilometers (1.2 miles) around the three frontline towns and is seen as a small step forward in Ukraine's stalled peace process.

The conflict erupted after Moscow annexed Crimea from Ukraine in March 2014.

Kiev and the West accuse Russia of fuelling the conflict, which has killed more than 9,640 people. Moscow however denies government involvement.

A peace deal brokered by Germany and France in February 2015 reduced the intensity of fighting but has failed to stop it. (voa/ez)