In early 1970, the mysterious murder of Acap Okoya, the sole rival to Amin among the senior military officers, led Obote to grow suspicious of Amin. Later that year, Obote escaped another assassination attempt after the attackers mistakenly targeted the car of the vice-president. However, Obote could take no direct action as he was totally reliant upon the army that Amin led to keep him in power. In response, Obote increased the recruitment of ethnic Acholi and Langi to counter the recruitment by Amin of soldiers from his home West Nile sub-region. In October 1970, Obote put Amin under house arrest on charges of increasing military expenditure over budget, as well as continuing to support Sudan's Anyanya rebel group in the civil war against the government of Gaafar Nimeiry, after Obote had decided to switch his support to Nimeiry. Amin was close friends with several Israeli military advisors that were helping to train the army and there is much speculation that they had influenced him to continue supporting the Anyanya, which was also the recipient of Israeli military aid.