BELGRADE, Serbia - NATO is holding an emergency exercise drill in Montenegro while Russian troops will participate in a war game in Serbia as the two Balkan neighbors seem to be heading in different directions strategically. The moves come amid mounting tensions between Russia and the West over a variety of geopolitical issues.

The five-day drill in Montenegro that started Monday includes fighting floods and chemical attacks. It will involve 680 unarmed personnel from seven NATO countries and 10 partner states.

The 13-day armed exercise in Serbia, dubbed “The Slavic Brotherhood 2016,” begins Wednesday. It will include 150 Russian paratroopers, 50 air force staffers, 3 transport planes and an unspecified number of troops from Serbia and Belarus, Russia’s Defense Ministry said.

Both Serbia and Montenegro - a single state before their split in 2006 - are traditional Russian Christian Orthodox allies. But since the split, Montenegro has pursued pro-Western policies, while Serbia has been struggling to wrestle away from the Moscow grip.

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Montenegro has been invited to join NATO, despite strong opposition from Russia. Serbia is under strong pressure from the Kremlin not to join the Western military alliance or the European Union.

Serbia, a NATO partner, has held exercises with the Western alliance, but not such a large one or with foreign troops and equipment participating on its soil.

Montenegrin officials have accused Russia of standing behind an alleged coup on election day earlier in October to topple the pro-Western government because of its NATO bid. Some 20 Serbian citizens were arrested in Montenegro during the vote, suspected of trying to stage the coup, while Serbian authorities reportedly deported an unspecified number of Russian operatives from their territory.