There are no problems which we cannot solve together, and very few that any of us can settle by himself.

Lyndon B. Johnson (1908–1973) American politician, educator, US President (1963–69)

Speech (1964-11-28), Press Conference, LBJ Ranch, Johnson City, Texas
    (Source)

Regarding the Atlantic Alliance (NATO). Variant: "There are no problems we cannot solve together, and very few that we can solve by ourselves."