Complex sentence: In May Russia increased the number of its peacekeepers in Abkhazia to 2,542, but its troop levels remained under the limit of 3,000 imposed by a 1994 decision of Commonwealth of Independent States heads of state.
Split into simpler sentences: In May Russia increased the number of its military peacekeepers in Abkhazia to 2,542. Even after the increase, troop levels still remained within the 3,000 limit imposed by a 1994 decision of Commonwealth of Independent States heads of state.