“Current technology could be used for deflection if we have sufficient political will and informed educated population” Prof. Joel Marks, Professor Emeritus of Philosophy

Due to their short warning time and great impact compared to their size, comets are a much greater danger than asteroids, and here no 1+ years deflection methods are usable because we won’t get that long a warning.

Any effective deflection mission will take a lot of time, unless we have already got a kind of deflection infrastructure ready and available to be used before detection. Hence, there is a great need to have two ongoing main efforts: One effort to enhance the detection capabilities and another to enhance the deflection capabilities.

More about the danger of comets – National Geographic