(…وَالَّذِينَ كَفَرُوا بَعْضُهُمْ أَوْلِيَاءُ بَعْضٍ ۚ…) (And those who disbelieved are allies of one another): This describes the situation at that time with the Jews and the polytheist Arabs, how they formed alliances and supported each other against the Prophet Muhammad (saws).
Similarly, it reflects contemporary situations, such as the alliance between Israel, the United States, and the West, against the nations, and this corresponds to the saying of Allah (swt) (And those who disbelieved are allies of one another.)
…إِلَّا تَفْعَلُوهُ تَكُن فِتْنَةٌ فِي الْأَرْضِ وَفَسَادٌ كَبِير)) (If you do not do so, there will be fitnah on earth and great corruption): Meaning, if you do not avoid the polytheists and support the believers, and unite as one cohesive entity, as Allah has emphasized in this strong bond of faith, then there will indeed be strife and immense corruption. Those aggressors, criminals, and killers among the Jews and the polytheists of the Arabs will infiltrate and sow discord among you.
History itself testifies to the truth of the Quranic statement, as each day reveals the involvement of the Jews and enemies of Islam in the crimes that we witness before our eyes and in all that unfolds.