NATO on Monday announced it would begin surveillance flights over Romania and Poland to better keep tabs on the security situation in Ukraine, Reuters reported.
Ukraine is not a member of the 28-state alliance. However, Russia's military occupation of Ukraine's Crimean Peninsula has unnerved some East European members of NATO, such as Poland and Lithuania.
The airborne early warning and control flights that NATO intends to begin conducting will take off from home bases in the United Kingdom and Germany, according to an alliance spokesman.
"These flights will enhance the alliance's situational awareness and all will take place solely over alliance territory," the unnamed spokesman said, adding that the surveillance flights will begin shortly and continue as long as necessary.
Tensions between the nuclear-armed counterparts -- NATO nations and Russia -- have risen to one of their highest points since the end of the Cold War. U.S. and European officials have warned that Russia could be sanctioned if it does not withdraw from Ukraine. Moscow has responded by suggesting it could halt onsite inspections under the New START arms control accord with the United States.
The Pentagon on Monday said it was critical for Washington to reassure its European allies of its commitment to their security.
"This is an important time for us to make crystal clear to all our allies and partners in the region that the United States of America stands by them," Defense Department spokesman Army Col. Steve Warren said in a Pentagon press story.
To reassure Poland, the United States has agreed to send extra F-16 jets to the country. The additional planes would come from U.S. European Command. The final number of planes has not yet been determined, according to Warren.