I recommend some international, as if things go south in the U.S., the int'l stocks may fare better...thus providing some diversification. Although I don't have any data, it seems to me that int'l ETFs/funds tend to be more volatile than U.S. based funds. I keep about 15% of my equities in int'l, but then I'm only about 25% equities all told...so that means only 3-4% of my total is int'l.
If you buy int'l, check out the composition. I like more "developed" country risk, so I find funds with Europe, Japan, Taiwan, South Korea, etc. For example, I would not invest in something like GQGIX, which has 30% of it's holdings in India and 14% in Brazil...or any fund with a lot of exposure in Africa.