Russia has warned it might field nonstrategic missiles along its territorial boundaries as well as in Belarus should negotiations with the United States on participation in a planned European antimissile framework prove unsuccessful, a high-level diplomatic insider said on Monday in remarks reported by Reuters.

Moscow fears that a U.S. plan to field increasingly advanced sea- and land-based missile interceptors around Europe over the next decade could undermine Russia's nuclear deterrent; it has sought from Washington a legally enforceable pledge that its missile interceptors would not be aimed at Russian nuclear forces. The United States maintains that the antimissile systems are focused on thwarting potential ballistic missile attacks from the Middle East. Both Washington and NATO have demurred from offering the pledge sought by Russia.

Krasnodar, an area in far western Russia, and Belarus could host Iskander missiles if the dispute is not resolved through dialogue, the insider told Interfax. Moscow in the past indicated it could place missile firing units in Kaliningrad, a Russian jurisdiction on the Baltic Sea.

"Earlier, only the Kaliningrad region was slated for Iskander missiles' deployment. But the possibility of deploying these complexes in Belarus and also in the Krasnodar region is also being considered. This would enable Russia to ward off threats to its strategic nuclear forces in case components of the United States' missile defense system are deployed near our borders," Interfax quoted the insider as saying

Moscow's response might also include additions to its air and aerospace defenses and to its space-based missile detection apparatus, the insider added.

Russia could also implement moves previously announced by President Dmitry Medvedev in response to a since-abandoned Bush-era missile defense plan involving Poland and the Czech Republic. "These include suspending the dismantling of missile regiments in the Kozelsk division of the strategic [missile] forces, creating radar capable of suppressing U.S. antimissile defense radars and strengthening the Russian navy," the insider said.

Meanwhile, a former top U.S. envoy to Ukraine called for the former Soviet state to determine soon whether it would join NATO's planned antimissile framework, Interfax reported.

"If Ukraine does not hurry, it may fail to find a place in this architecture. In recent years, we have seen that Ukraine gives conflicting signals on whether it will participate or will not participate (in the European missile defense system)," former U.S. Ambassador Steven Pifer said.

Ukraine might first want Moscow to take a stance regarding involvement in the system, but the nation should make its own assessment of potential dangers, Pifer said, adding that missile-tracking systems in Ukraine could benefit the alliance's defenses.

"But I do not think that NATO will push Ukraine toward something. It has to decide for itself what to do," the former official said.