In 2007 Uranus and Pluto began to approach square aspect but approached and receded without forming an exact square, until now, or more exactly, until June 24, 2012. They will remain within 5 degrees of square until June 2015. During this time they will form seven exact square aspects, after which they again approach and recede but do not again form an exact square until February 2073.
The dates and times of the seven exact squares in 2012-2015 are given in the
Transit Table for Uranus-Pluto 2000-2022, which was made using the
Your Planetary Transits software. That program (which introduces a new method of displaying planetary transit data) also tells us that after the Uranus-Pluto squares of 2012-2015 the next exact hard aspect between these planets, an opposition, occurs in 2046-2048 (five times).
The Uranus-Pluto squares of 2012-2015 might nicely coincide with a possible global war (fought over control of economically valuable resources, and with one side attempting to successfully implement its plans for global dominance), since events in various parts of the world seem to be leading up to that. If you make it through alive (good luck! -- you'll need it) then you can look forward to five exact Uranus-Pluto trines in 2026-2028.