Answer:
Mexico not willing to give up Mexican/American soil to the US to get annexed , the plot of land that was disputed was Texas and wheater it ended at Nuecas River or Rio Grande River , Texas wanted independance as its own country and thus started a civil war against mexico to gain its independance , USA saw this and said SIKE US started a war on Texas and won later annexing all of texas
Step-by-step explanation:
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