(وَإِمَّا تَخَافَنَّ مِن قَوْمٍ خِيَانَةً) (If you [have reason to] fear betrayal from a people,): Islam commands of the fulfillment of covenants. So, if it comes to your knowledge that they will be treacherous, do not attack them by surprise, rather:

( فَانبِذْ إِلَيْهِمْ عَلَىٰ سَوَاءٍ ) (Throw [their treatry] back to them.): This means to inform them and make it clear to them that their treaty is annulled. This is because Islam is not limited only to Muslims, Allah (swt) says in the Quran:

 إِنَّا أَنزَلْنَا إِلَيْكَ الْكِتَابَ بِالْحَقِّ لِتَحْكُمَ بَيْنَ النَّاسِ بِمَا أَرَاكَ اللَّهُ ۚ وَلَا تَكُن لِّلْخَائِنِينَ خَصِيمًا

(We have sent down to you the Book in truth so you can judge between the people by what Allah has shown you. And do not be an advocate for the deceitful) (An-Nisaa’: 105)

Allah (swt) commands the Prophet (saws) have to judge among the people. So that, if you fear treachery from a party, send to them and clarify with them that they have violated the covenant before any attack against them.

(إِنَّ اللَّهَ لَا يُحِبُّ الْخَائِنِينَ) (Indeed, Allah does not like the treacherous.): Similar expression is found in many Quranic verses:

وَاللَّهُ لَا يُحِبُّ الظَّالِمِينَ

(And Allah does not like the wrongdoers) (Ali-Imran: 57)

إِنَّ اللَّهَ لَا يُحِبُّ الْمُعْتَدِينَ

(Indeed, Allah does not like the aggressors) (Al-Baqarah: 190)

 فَإِنَّ اللَّهَ لَا يُحِبُّ الْكَافِرِينَ

(Indeed, Allah does not like the disbelievers) (Ali-‘Imran: 32)

Pondering upon those whom Allah does not like, we find them all characterized by elements of corruption and wrongdoing. What is expected of you is to always uphold righteousness, ethics, and values, even in dealing with those who have acted treacherously towards you. So, here, there is a responsibility to be firm, but you should, at the same time, convey to them that this covenant and agreement have been nullified due to theri treachery.