How to add UglifyJS to a VueJS project - vue.js

Question

I need to add UglifyJS to a VueJS CLI 3 project.
My vue.config.js:
var webpack = require('webpack')
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
module.exports = {
// ...
optimization: {
minimizer: [new UglifyJsPlugin()],
},
publicPath: "./",
plugins: [
// ...
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify('production')
})
]
}
This is the error message I get after trying to run npm run build.
Invalid options in vue.config.js: "optimization" is not allowed.
"plugins" is not allowed
I tried updating all packages and install the webpack UglifyJS plugin.
package.json
{
"name": "app",
"version": "0.1.0",
"private": false,
"scripts": {
"serve": "vue-cli-service serve",
"build": "vue-cli-service build",
"lint": "vue-cli-service lint"
},
"dependencies": {
"core-js": "^2.6.5",
"firebase": "^6.3.0",
"material-icons": "^0.3.1",
"register-service-worker": "^1.6.2",
"vue": "^2.6.10",
"vue-flickity": "^1.1.2",
"vue-router": "^3.0.3",
"vuetify": "^1.5.5",
"vuex": "^3.0.1"
},
"devDependencies": {
"#mdi/font": "^3.8.95",
"#vue/cli-plugin-babel": "^3.8.0",
"#vue/cli-plugin-eslint": "^3.8.0",
"#vue/cli-plugin-pwa": "^3.8.0",
"#vue/cli-service": "^3.8.0",
"#vue/eslint-config-prettier": "^4.0.1",
"babel-eslint": "^10.0.1",
"eslint": "^5.16.0",
"eslint-plugin-vue": "^5.0.0",
"material-design-icons-iconfont": "^5.0.1",
"stylus": "^0.54.5",
"stylus-loader": "^3.0.2",
"vue-cli-plugin-vuetify": "^0.5.0",
"vue-template-compiler": "^2.6.10",
"vuetify-loader": "^1.0.5",
"webpack": "^4.40.2"
},
"eslintConfig": {
"root": true,
"env": {
"node": true
},
"extends": [
"plugin:vue/essential",
"#vue/prettier"
],
"rules": {"no-console": "off"},
"parserOptions": {
"parser": "babel-eslint"
}
},
"postcss": {
"plugins": {
"autoprefixer": {}
}
},
"browserslist": [
"> 1%",
"last 2 versions"
]
}
How to add UglifyJS to the VueJS project?