WARSAW, Poland — Hundreds of NATO troops with heavy equipment began a military exercise in Poland on Tuesday, testing the alliance's rapid response readiness in the face of new security challenges on its eastern flank.

The so-called spearhead force was agreed upon at a NATO summit last year in reaction to Russia's role in the separatist fighting in Ukraine which has raised security concerns in other nearby nations that were once under Moscow's dominance.

"It is our unconditional priority to have NATO's eastern flank strengthened," Deputy Foreign Minister Henryka Moscicka-Dendys said when asked about the role of the Noble Jump exercises. "I feel safe."

The deployment exercise began with German and Dutch troops arriving near the southwestern Polish city of Zielona Gora to test the Very High Readiness Joint Task Force. It will soon move to a test range in nearby Zagan, where more than 2,000 troops will train.

A mobilization exercise was held in April in the Netherlands and the Czech Republic. The current exercise tests deployment procedures by road, rail and air.

Allied Shield exercises will be held this summer in the region and will involve 14,000 troops from 19 NATO members and three partner nations.

A multinational naval exercise opened on the Baltic Sea last week.