The increased military expansion in Europe before World War 1 caused alarm because of what?

The increased military expansion in Europe before World War I caused alarm due to the rising tensions among the major powers, as nations built up their armies and navies, creating an arms race. This militarization heightened fears of conflict, as countries formed rival alliances, which made the potential for a localized conflict escalating into a broader war more likely. The atmosphere of suspicion and competition contributed to a sense of impending crisis, ultimately setting the stage for the outbreak of war in 1914.