Russia has made clear once again that it doesn't want NATO forces on its borders. Or on its shores. Or anywhere near foreign territory it occupies.

Canadian Defence Minister Rob Nicholson has accused the Kremlin of sending three warplanes to buzz its navy frigate Toronto on Sunday while it was taking part in NATO exercises in international waters of the Black Sea.

The HMCS Toronto heads out of the harbour in Halifax, Nova Scotia. Credit:AP

"While the Russian military aircraft that circled the HMCS Toronto did not in any way pose a threat to the Canadian ship, their actions were unnecessarily provocative and risk escalating tensions even further," Mr Nicholson said.

The tensions he referred to emanate from months of fighting between Ukrainian troops and Russian-backed separatists in eastern Ukraine; a conflict inspired by Russia's seizure of Ukraine's Crimea region in late February and annexation of the strategic Black Sea peninsula in mid-March.