In the context of taps on international communications of those who have had previous communications with international terrorists. Yes indeed.
The Constitution is not a suicide pact, and it's protections do not extend to enemy combatants, spies or their supporters. Otherwise, if a foreign army took over part of the US, say the West Coast, we'd have to grant all their soldiers the right to keep and bear arms, the right of assembly, free press, etc. We could not conduct raids on their positions without a court order. Patently ridiculous of course, but that is where the logic of extending Constitutional protections to those with whom we are at war leads.
I am very skeptical of warrantless wiretaps of US citizens for any reason. Of course we should be listening to terrorist conversations, but get a warrant first.