what does this mean?

Obama is faced with a request from the American and NATO commander in Afghanistan, General Stanley McChrystal, for large numbers of new troops. The decision may define his presidency. Despite the difficulty—indeed, because of the difficulty—he should give the general what he needs.

The alternative is not, as some opponents of an Afghan “surge” suggest, less intensive, more surgical “counter-terrorism”, relying on unmanned air raids and assassination.

what does the second paragraph mean? Thanks.