Kirkup's 1966 poem "No Men are Foreign" focuses on the commonalities between all people. The poem's speaker states of foreigners:

They, too, aware of sun and air and water,

Are fed by peaceful harvests, by war’s long winter starv’d.

We are all united, the poet says, by sharing the same planet, as well as by work, by sleep, and by love. The speaker does not identify himself with any nationality, tribe, or group: he could be anyone from anywhere reaching out to fellow humans and expressing what we all share. This may reflect the fact that Kirkup, although English, did live in various parts of the world, including Asia and America.

The poem becomes an expression of anti-war sentiment as it states:

whenever we are told

To hate our brothers, it is ourselves

That we shall dispossess, betray, condemn.

When Kirkup ends the poem with the line:

no men are foreign, and no countries strange

he echoes John Donne's idea that "no man is an island." We are all one, bonded together in a common humanity.

Today we would most likely use the word human or humankind instead of "man" or "men" (also, we tend to call people from other parts of the world not foreigners, but internationals), but Kirkup means to include all genders in his poem. His simple, straightforward language makes a clear point: since we are all one, we should try to get along.

In this poem, the speaker argues that people and countries are all fundamentally the same. No person is really strange and no countries are so different. We all breathe the same air and walk the same earth, and we will all be buried in that one earth we share. All people experience the sun, eat the food the earth provides, suffer in the winter or during war. We all do the same kinds of work. We all have eyes, we sleep and we awaken, and we all love.

Every country shares a "common life" that we all recognize and understand. We should not hate one another because the "other" is truly ourselves. When we lash out against others, we hurt ourselves. When we fight, we defile the earth we share, polluting it and corrupting the purity of the air we breathe. In the end, we are all alike.

This poem by James Kirkup begins and ends with the same line, with the repetition serving to emphasize the fact that this is the core message of the poem:

Remember, no men are strange, no countries foreign.

The subject of this poem is the unity of the human race, despite differences in race, geography or language. All people are "brothers," in that we all walk on the same land and will be buried under it. This comment highlights the poet's point that we are all, ultimately, related, and are all born the same and will die in the same way. Use of language like "uniforms" suggests that even in times of war, the opposing sides would do well to remember that under the uniforms, "a single body breathes."

The poem covers various points of similarity between people from all countries: people have "hands" like ours, they "labour" as we do, and they have "eyes like ours that wake" to see a similar world. Hating other people because they are different, or raising arms against other people, is effectively a condemnation of ourselves: "it is the human earth that we defile."

This poem could be understood as a protest against such issues as racial hatred and warfare, which threaten the peace and safety of human beings in similar ways.

As the title of the poem implies, this is a poem about the brotherhood of all men.  The author is trying to argue that all people are essentially the same.  He uses the word "foreign" to mean "different" and argues that we should not see other people as foreign or different just because they come from some other country.

The author argues that all people share the same sorts of dreams and aspirations and problems.  He says that this is why they are all similar to each other.  He concludes by arguing that this is why there should be no war.  He says that war is unnatural because it is like fighting against ourselves.