BELGRADE (Reuters) - Serbia and Russia began joint military exercises on Serbian territory on Thursday in a move likely to reinforce increased east-west tensions just as a five-day NATO drill in neighboring Montenegro draws to a close.

Serbia is trying to balance its traditionally warm ties with Russia, a fellow Slavic, Orthodox Christian nation, with its push for membership of the European Union and closer relations with NATO, though it has no plans to join the Atlantic alliance.

In the exercise dubbed “Slavic Brotherhood”, which runs until Nov. 9, more than 700 troops from Serbia, Russia and Belarus will stage helicopter assaults, a mock attack on an insurgent base, evacuate casualties and practice artillery bombardment.

“It will all be very attractive,” defense ministry spokesman Jovan Krivokapic told Tanjug news agency.

The launch of the exercise coincides with the end of the NATO drill in Montenegro, which focused on handling emergency situations such as floods or chemical attacks that included 680 unarmed personnel from seven NATO members and also 10 partner countries including Serbia.

The exercise also coincides with a deep chill in relations between Russia and the U.S.-led Atlantic alliance.

NATO has announced plans to send troops, tanks and planes to the Baltic states and Poland to counter what it perceives as a more assertive Russia following Moscow’s annexation of Crimea from Ukraine and other actions.

Serbia, which relies on Russia for energy, is not actively seeking membership of NATO, which remains unpopular among Serbs because of its 1999 bombing campaign to drive Serbian forces out of Kosovo.

But as part of its integration with the West, Serbia last year signed the Individual Partnership Action Plan (IPAP), the highest level of cooperation between NATO and a country not aspiring to join.

Since 2006, Serbia has held 1,400 various activities with NATO, including 197 last year. In 2016, out of 26 training exercises only two are with Russia. Out of 21 multinational training drills in 2015, the Serbian military participated in only two with Russia.

Montenegro, which split from Serbia a decade ago, accepted an invitation last year to join NATO, angering Moscow.

Last month Montenegro’s outgoing Prime Minister Milo Djukanovic accused Moscow of meddling in his country’s parliamentary election campaign and of financing the opposition.