Funny thing, I just saw a review of a new book by H.W. Brands, "The Strange Death of American Liberalism." Brands argues that the mid 20th century successes of liberalism were a result of the Cold War. With the Cold War over, in Brand's view liberalism will recede. On the last page of the book: "(Of course in the presence of a renewed security threat, the liberals will once again be called to power -- QED)."
I don't know if the first two propositions are valid, but the third may well come true. Maybe Brands inserted that last bit after 911, but this is a strange case of a book being both obsolete and exceptionally timely even before it's published.
If history is any guide, we may see not just new security measures, but more general social policies and social changes designed to win us support in other parts of the world in our current war.
I have no idea what Brands means. The statement is much too vague. Besides, what kind of "liberalism" does he mean -- Rooseveltian socialism or multiculturalism's racial socialism? At this point, notwithstanding all the claims that "everything has changed" since 911, I don't see racial socialism's death grip on America weakening one bit, npot with "radical rightwing" presidents me-tooing us to death.
Aside from that, I think your last statement is -- unfortunately -- correct. We are going to spend much more than even before trying to buy friends abroad, who will ultimately either be fair-weather friends (see the government of Saudi Arabia) who stab us in the back, when we call in our markers, or our worst enemies, who murder our citizens (see the Saudi rulling class).