Thousands of Central American migrants resumed an arduous trek toward the U.S. border Monday, with many bristling at suggestions there could be terrorists among them and saying the caravan is being used for political ends by U.S. President Donald Trump. The caravan's numbers have continued to grow as they walk and hitch rides through hot and humid weather, and the United Nations estimated that it currently comprises some 7,200 people, "many of whom intend to continue the march north." However, they were still at least 1,140 miles (1,830 kilometers) from the nearest border crossing - McAllen, Texas - and the length of their journey could more than double if they go to Tijuana-San Diego, the destination of another caravan earlier this year. That one shrank significantly as it moved through Mexico, and only a tiny fraction - about 200 of the 1,200 in the group - reached the California border. The same could well happen this time around as some turn back, splinter off on their own or decide to take their chances on asylum in Mexico - as 1,128 have done so far, according to the country's Interior Department.