Complex sentence: They protested the illegal Israeli military blockade of the occupied Palestinian Gaza Strip, after the Israeli military blocked unarmed civilian aid ships with the Free Gaza Movement attempting to enter the Gaza's territorial waters on their way to Gaza.
Split into simpler sentences: They protested the illegal Israeli military blockade of the occupied Palestinian Gaza Strip. The Israeli military intercepted civilian aid ships with the Free Gaza Movement attempting to enter the Gaza's territorial waters on their way to Gaza.