Uganda will withdraw its forces from UN-backed international missions, Security Minister Muruli Mukasa says, escalating a long-running row.
Mr Mukasa said the government had sent an official to New York to inform the UN of this decision.
Operations in Somalia, the Central African Republic and the Democratic Republic of Congo will be affected.
The UN infuriated Kampala when it published an experts' report accusing Uganda of arming Congolese rebels.
Mr Mukasa told a news conference: "If our efforts are going to be misinterpreted and we are going to be maligned, we want to be in a good relationship with our neighbours.
"Let's stop all these initiatives. We will concentrate on ourselves. Whoever wants to cause us trouble, they will find us at our home."
Uganda provides the largest contingent to the UN-backed African Union mission in Somalia (Amisom).
The Amisom force has helped the Somali government gain ground against Islamist militias.
Analysts say a rapid withdrawal of Ugandan troops could threaten those gains.
Ugandan troops are deployed in smaller numbers to an international mission to CAR and DR Congo to hunt down the remaining elements of the Lord's Resistance Army and its leader, Joseph Kony.
The LRA killed thousands of people and abducted thousands more during a long insurgency that has seen it fight in several countries.
The remarks from the security minister echo a statement made in the Ugandan parliament on Thursday by Prime Minister Amama Mbabazi.
The BBC's Catherine Byaruhanga in Kampala says while both the prime minister and the security minister have said the decision is irreversible, there has been no official government word on the issue.
The foreign and defence ministries, when contacted by the BBC, said no statements were available.
A report by a UN panel of experts last month said Rwanda and Uganda were both supplying weapons to the M23 rebels in the DR Congo. Both countries denied the claims.
The rebels' insurrection has forced some 500,000 from their homes since April.