With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: After 1945, proposals to introduce tolls to the seaway were not sufficient to gain support for the project by the U.S. Congress. Growing impatient, and with Ontario desperate for the power to be generated by hydroelectricity, Canada began to consider developing the project alone. This seized the imagination of Canadians, engendering a groundswell of nationalism around the St. Lawrence. Canadian Prime Minister Louis St. Laurent advised U.S. President Harry S. Truman on September 28, 1951, that Canada wanted to wait for the United States and would be unwilling to build a seaway alone; however, the Canadian Parliament authorized the founding of the St. Lawrence Seaway Authority on December 21 of that year. Fueled by this support, Saint Laurent's administration decided during 1951 and 1952 to construct the waterway alone, combined with the Moses-Saunders Power Dam. (This became the joint responsibility of Ontario and New York: as a hydropower dam would change the water levels, it required bilateral cooperation.)
text_B: Was Truman probably shocked by the Canadian Parliament's authorization of the waterway on December 21?
YES.