Because he wanted to bring peas to the Middle East.
Explanation: This joke is a pun on the words “peas” and “peace.” The humor comes from the play on words, where “peas” (the vegetable) sounds like “peace.” The punchline humorously suggests that the speaker is bringing actual peas (frozen vegetables) to the Middle East, but it also implies that they are symbolically “bringing peace” to the region, which has historically faced conflict.